California Independent Study Charter Schools: Summary of Home-Based Pedagogies, Enrollment Trends, and Student Demographics

ABSTRACT

The purpose of this study was to establish historical enrollment trends, student demographics, and home-based pedagogies of nonclassroom-based schools in California in an effort to gain insights into lesser-known homeschooling practices. According to the United States Department of Education, in 2016, homeschooling had progressively increased to 3.3%. To determine whether California has a similar trend in students’ learning outside of a traditional classroom-based learning environment, we evaluated eight years of student enrollment data from the California Department of Education. Potential implications for this student population in relation to California’s vaccination legislation, as well as the impact of the Covid-19 pandemic, are explored. The demographic information of nonclassroom-based public school students in California was summarized and compared to that of classroom-based students in California and homeschooled students in the United States, finding less ethnic diversity in nonclassroom-based schools. Our findings of home-based pedagogies suggest families of California nonclassroom-based charter schools lean more toward a standards-based, traditional (57.8%) pedagogy, followed by Classical (10.8%) and Project/Unit-based (9%).

Introduction

The modern homeschooling movement originated in the 1970s, predominantly from the desire of Protestant parents to provide their children with an alternative education that was more compatible with their religious beliefs and ideological backgrounds; however, many child-centered families homeschooled with the goal of improving their children’s education (Stevens, 2001; Van Galen, 1991). During the mid-1970s, an estimated 0.03% of all school-age children were homeschooled (Lines, 1999). During the 1980s, homeschooling parents in the United States sought the legal right to do so, as homeschooling was considered to be a form of truancy (Isenberg, 2007). After a series of successful legal battles, homeschooling was legalized in all 50 states by 1993 (Angelis, 2008). Since then, parents have become increasingly aware of this alternative educational option through the expansion of available means of homeschooling, particularly through the disruption in K-12 education caused by the Covid-19 pandemic. In an effort to quantify this segment of K-12 education, in 1999, the U.S. Department of Education’s National Center for Education Statistics (NCES) at the Institute of Education Sciences began collecting nationally representative data (McQuiggan & Megra, 2017; Snyder, de Brey, & Dillow, 2019), when it was estimated that 1.7% of all children between ages 5 and 17 were homeschooled. The most recent data from the 2016 academic year indicate an increase to 3.3% nationally, or 1,689,726 children being homeschooled in total, according to NCES.

The growth in the percentage of homeschooled students in the U.S. over the past two decades has been accompanied by an increase in the scholarly research on this nontraditional form of K-12 education. Kunzman and Gaither (2020) wrote a comprehensive summary of homeschooling research, distilling the body of research and grouping it in the following eight general topics: student demographics; motivation of parents to homeschool; homeschool curricula and practice; academic outcomes; socialization of children; psychological and physical health; legal aspects of homeschooling; relationships with U.S public schools; and international homeschooling. In this paper, we will take a detailed descriptive look at independent study charter schools in California, thus contributing to the scholarly research on homeschooling in the areas of (1) student demographics and enrollment trends; (2) legal aspects of homeschooling; (3) curricula and home-based pedagogies; and (4) relationships with public schools. We will also discuss the potential implications of the Covid-19 pandemic on the demographic enrollment trends of nonclassroom-based schools as well as homeschooling in general.

At the state level, demographic data for homeschooled students in the U.S. have been limited because individual states have inconsistent reporting requirements for parents electing to homeschool their children (Isenberg, 2007). As a result, researchers must rely on volunteer parent survey results to gain demographic insights into this historically elusive segment of K-12 education. Currently, the most comprehensive national student demographic data are collected every 3 to 4 years by the National Household Education Survey with voluntary parent surveys (Snyder et al., 2019). To compound this issue, it has been reported that parents of homeschooled children have demonstrated a reluctance to complete government-sponsored surveys about their children and household (Kaseman & Kaseman, 2002; Lines, 2000; McPhee et al., 2015). Public schools that offer nonclassroom-based, homeschool-like educational programs, such as California independent study charter schools, may help to provide a more complete demographic profile of a particular geographical region for homeschooled students, as that demographic information is required by the families at the time of enrollment and is publicly available.

State laws requiring vaccines for all classroom-based students may have unintended consequences in terms of increasing the percentage of homeschooled students. In June 2015, the California Senate signed into law the Senate Bill (SB-277), removing the personal belief exemption for required school vaccinations. Committee hearings on this bill indicated that California would be denying free public school education to the children of parents choosing not to vaccinate through such an exemption, according to the California Constitution, Article IX – Section 9, written in 1879, guaranteeing a free public education for all children. For this reason, SB-277 was amended to allow California independent study charter schools to enroll students with a personal exemption waiver for vaccines. Senate Bill 277 went into effect on July 1, 2016. Currently, new legislation in California is being proposed and debated that would require Covid-19 vaccines for all students attending a classroom-based public or private school. If the proposed legislation is signed into law, home-based education would be the only remaining educational option for California parents choosing not to vaccinate their children with the Covid-19 vaccine, or other required school vaccines.

According to Kunzman and Gaither (2020), researchers have been challenged to summarize and describe the variety of homeschooling practices and curricula because of the wide variety of approaches used by families (Neuman & Guterman, 2017), as well as the difficulty researchers have experienced in gaining access to homeschooling families. It has been reported that some homeschooling families adhere to a well-structured, more formalized instructional day (Gann & Carpenter, 2019; Neuman & Guterman, 2017; Taylor-Hough, 2010), whereas other studies have discovered that homeschooling families lean toward an eclectic approach in regard to curricula and instructional strategies (Bachman & Dierking, 2011; Kraftl, 2013). Also, the home-based pedagogy of homeschooling families does not appear to remain static over time. According to a 10-year longitudinal study of 225 homeschooling families in Pennsylvania (Hanna, 2012), homeschooling families have evolved their homeschooling approaches as their children matriculate in their schooling. Of the research studies done to date, limited sample sizes of homeschooling families have made it difficult to gain a macroview of the generalized types of instructional approaches used by homeschooling families in the U.S. This is particularly challenging when attempting to describe a segment of K-12 education known for a nontraditional and nonconforming approach to learning.

In California, the relationship between homeschooling families and public schools is formalized through independent study charter schools, a type of nonclassroom-based school. To clarify terminology used in this paper to describe nonclassroom-based schools, the term independent study charter school is formally used in the California Education Code to describe public schools that offer nonclassroom-based learning. Such schools in California are also described as personalized learning schools. The term homeschooled is used in this paper to describe children who are educated through a Private School Affidavit (PSA) in California; these students are not enrolled in a public independent study charter school and are instead privately educated at home. As a further point of clarification, California independent study charter schools are largely not online schools. Many nonclassroom-based charter schools in California are structured to support home-based learning, which in many ways, resembles the pedagogy of privately homeschooled families.

The relationship between homeschooling families and California public schools has been in the making for the past three decades. In 1992, California Senator Gary Hart introduced SB1448, a bill that legally allowed the formation of charter schools in California and opened the door for the development of nonclassroom-based independent study public charter schools. Each state differs in the policies and options available for alternative, nonclassroom-based students, with and without public education fund involvement. Parents interested in educating their child outside a traditional classroom-based school have three options in California: (1) file a PSA with the California Department of Education (CDE); (2) enroll the child in an independent study charter school; or (3) enroll the child in a blended learning school, where part of the instructional time occurs in a classroom and the rest is done at home.

For the first option, the California parent must file a PSA online with the CDE before October 15th of each year to be considered a private school (i.e., legally homeschooling). No public funds support such private schools; there are no required state-mandated assessments, no reporting or required standards-based instruction, and there is no required credentialed teacher oversight. The parent provides the entire curriculum and all educational services for the education of their child and determines when the child has met the requirements for graduation.

For the second option, some independent study charter schools are purely online, but most offer a diverse curriculum, both textbook and digital, and support instruction through a local network of school-approved community partners that offer in-person tutoring and instruction. As public schools, such organizations assign a credentialed teacher to every student enrolled at a 25:1 student-to-teacher ratio, in accordance with California Education Code 51745.6(d). The credentialed teachers work closely with the parents and students to develop a personalized learning plan. Public charter school funds are used to purchase necessary standards-based curriculum and to pay for instructional activities. Furthermore, such schools may have classroom facilities for group classes, but the facilities must be located within the authorizing school district’s boundaries, and the instructional time must comprise less than 20% of total weekly instruction. Alternatively, students may also receive 100% of their weekly instruction outside the classroom.

Classroom-based California charter schools require a minimum of 20% weekly classroom instructional time, though most provide 100% of instruction in the classroom. Due to this flexibility, some classroom-based charter schools have developed an academic schedule that allows for some instruction at home. In this paper, the term blended learning school (also referred to as hybrid schools) is used to describe K-12 schools that offer a combination of traditional classroom-based learning and independent study charter school-style learning. A student enrolled in such a school might attend classes at a classroom-based school facility on Tuesdays and Thursdays, while learning at home on Mondays, Wednesdays, and Fridays, a schedule similar to that of an independent study charter school student. Flexibility is afforded in assigning class schedules if the classroom instructional time exceeds 20% of total instruction per week.

A study was conducted to explore and summarize the demographics, enrollment trends, and pedagogy of home-educated public charter school students enrolled in three California independent study charter schools. Those schools do not require students to use school-adopted curricula or follow a particular pedagogy, other than meeting California State Content Standards for the student’s grade level. Parents are allowed to select the curricula and home-based pedagogy. As such, the results presented in this paper, based on a large sample size (n = 5,511), may help to provide insights into the homeschooling practices of the more elusive PSA students in California and privately homeschooled students in the U.S. Enrollment trends and demographic information of nonclassroom-based K-12 education in California will be illustrated, and the enrollment implications of the Covid-19 pandemic on homeschooling will be discussed.

Methods

The California independent study charter schools participating in this study were South Sutter Charter School, Ocean Grove Charter School, and Sky Mountain Charter School, all of which were accredited through the Western Association of Schools and Colleges. Students in grades K-12 resided in 18 counties throughout northern and southern California, representing students from rural, urban, and suburban communities (Figure 1). According to California Education Code 51747.3(b), an independent study charter school may enroll students in any county contiguous to the county of the authorizing school district. Hence, Ocean Grove Charter School is authorized in Santa Cruz County; Sky Mountain Charter School is authorized in San Bernardino County; and South Sutter Charter School is authorized in Sutter County.

Figure 1. Map illustrating the counties of enrolled students served by Ocean Grove Charter School, Sky Mountain Charter School, and South Sutter Charter School.

All participating schools were established and are managed by Innovative Education Management, a nonprofit charter school management organization. The approved charter language and identical school policies, teacher training, and instructional resources available to students are similar for each of the schools. For the 2015/2016 academic year, $2,200 of instructional funds was allocated for each student in grades TK-8, and $2,700 was allocated for each student enrolled in grades 9–12. The credentialed teacher assigned to students was responsible for using these instructional funds to purchase the necessary curriculum materials and educational services to support each student’s personalized learning plan, which also aligned with grade-level California Content Standards.

The participating independent study charter schools were structured to support strong parent involvement in the selection of curriculum and pedagogy they would utilize to educate their child at home. Since parents often enroll their children in one of these independent study charter schools with the goal of educating them at home in a particular way, teachers working at these schools were well-trained in a wide variety of curricula and home-based pedagogy used by homeschooling families. In fact, since 2005, participating independent study charter schools have created professional development training for teachers on a diverse range of homeschooling pedagogy and curricula that parents commonly use.

The term educational philosophy is commonly used at these three participating schools and by similar independent study charter schools in California, as well some PSA homeschooling parents. For the purpose of this paper, we use that term to describe the type of home-based pedagogy, curricula, and instructional delivery modality used in home-educated settings. In an effort to capture the distribution of educational philosophies used at the three independent study charter schools, school administrations required all teachers to complete a survey to identify the educational philosophy for each of their students so that the school administration could use that information to plan future professional development sessions for their teachers. The decision to survey teachers instead of parents was made because the credentialed teachers had been formally trained in distinctions between the different educational philosophies and instructional modalities; therefore, assigned teachers would be able to objectively identify the appropriate educational philosophy for each student, if known. The decision to identify the educational philosophies based on the student and not the parent was made because some families with multiple children may have different educational philosophies based on the unique learning styles, personality types, and individual learning plan of each child.

In February 2016, credentialed teachers from the three participating schools were surveyed regarding the educational approaches used by each student assigned to the teacher. A comprehensive list of educational philosophies was presented, and teachers were asked to indicate, from their perspective, one or more of the philosophies followed by the parents of each of their students. Teachers were then presented with the same list of educational philosophies in a subsequent question and were asked to choose a single option from that list to indicate the educational philosophy that best matched the student’s family. Educational philosophy options used in the survey were the same ones listed in Table 1. Surveys were conducted using the Qualtrics (Qualtrics, Provo, UT) online survey software (version 02.2016). A high survey completion rate of 100% was obtained because it was a required task for all teachers at the participating schools, and completion was verified by school administration. In this study, a total of 309 teachers, representing 5,511 students, completed the survey.

Table 1. Summary and description of educational philosophies followed by the parents of students enrolled in California independent study charter schools.

Educational Philosophy	Distinguishing Characteristics	Instructional Approaches	Examples of Curriculum
Charlotte Mason	Charlotte Mason’s approach to home education during the late nineteenth century is summarized in three words: atmosphere, discipline, and life. Atmosphere describes the environment of experiences children have as they learn through a diversity of direct experiences. Discipline describes the emphasis placed on intrinsic motivation for learning by children, which is unique for each child. Life describes how students learn history through historical based novels rather than textbook summaries. Children build on understanding through the engagement of reading high quality literature, the retelling of stories with imagination, and encouraging the curiosity of the natural world around them through first-hand experiences by forming hypotheses and making connections.^a	Charlotte Mason believes that students are intrinsically motivated and learning is assimilated through observing and interacting with their environment. The role of the adult educator is to provide encouragement and appropriate stimuli for the child through scaffolding that encourages the child to develop questions and reason about the world around them, in an effort to bridge relationships and connections with prior knowledge. Outdoor learning is promoted through local nature walks and museum visits. Children are encouraged to demonstrate learning through role-playing, retelling or narration, and through creative expressions in art.^b	Brave Writer Math-U-See Right Start Math Simply Charlotte Mason Sassafras Science
Classical	Classical homeschooling is built on three stages of learning (Grammar Stage, Logic Stage, and Rhetoric Stage) based on the cognitive developmental phases of a child. In each stage, students continue to learn grammar, logic, and rhetoric. Children are often taught to write in cursive and Latin is typically learned as a foundational language. Classic literature is used to teach history, ancient through modern history, sequentially and repeated through the grade levels. Primary historical documents are used instead of textbook summaries. Logic and debate skills are emphasized. Grammar, logic and rhetoric are viewed as essential learning tools for the learning of all subjects.^c	In the Grammar Stage (grades K-6), children learn grammar, syntax and vocabulary through songs and chants. Emphasis is placed on direct instruction, reading and discussion. In the Logic Stage (grades 7–9), instructional activities emphasize argument, discussion and debate. Writing activities include compare/contrast and argumentative through the process of research. In the Logic Stage, children will learn the process of research. Instructions are given on how to identify false logic through the practice of formal debates. In the Rhetoric Stage (grades 10–12), children are encouraged to form their own opinions through the synthesis and analysis of information and then persuasively communicate those opinions or academic positions. It is expected that the development of arguments is to be based on reason, both in the written and oral forms.^c	The Critical Thinking Company Easy Grammar/Daily Grams Elemental Science Great Books Foundation Institute for Excellence in Writing Saxon Math Story of the World The Well-Trained Mind
Delayed Academic Approach	The Delayed Academic Approach is likely the most loosely defined educational philosophy in homeschooling. Very little is written on the topic, though the concept is occasionally discussed by parents. Homeschooling parents who follow this instructional approach say that children are ready to learn academic concepts at different times in their development, and children should not be forced to learn particular concepts or skills based on their age level. Parents who follow this educational philosophy often pair it with another educational philosophy listed on this table. Although the word ‘delayed’ implies that a child will be introduced to academic concepts later than his/her peers, the Delayed Academic Approach may also result in a child learning concepts and skills at an age younger than his/her peers, such as learning to read.	While most of the educational philosophies start formal education at the kindergarten grade level, a homeschooling family following a Delayed Academic Approach may not start a formalized academic program for their children until grade 3, or later. Play is strongly encouraged for children in grades K-3 in an effort to encourage creativity, communication, and problem solving. Subject area content may take a Project/Unit-based approach to homeschooling at the younger grades, with the goal of assessing a child’s readiness for more formalized instruction. Occasionally, this educational philosophy is used with older children (grades 8–12), particularly in the subject of mathematics.	Key to Series Usborne Books Zaner-Bloser
Montessori	Developed by Maria Montessori in the early 20th century, this is a child-centered educational approach based on scientific observations of children from birth to adulthood. Montessori is an individualized educational approach to learning that is driven by a child’s interest to learn on his/her own, rather than directed from an adult authority. Current Montessori curriculum is organized with five learning domains – practical life, sensorial, language, mathematics, and culture. As students progress, they transition from reading and writing to develop rational problem solving in the middle school years. By high school, “children reconstruct themselves as social beings and are humanistic explorers, real-world problem solvers, and rational seekers of justice.” ^d	Learning occurs in multi-age student groupings with child-sized materials and manipulatives where students are encouraged to work at their own pace. Parents observe and guide learning, more so than instructing and directing. Student motivation occurs from the child’s inherent curiosity and desire to learn. Students are involved in the self-correcting of their work. Self-discipline of the child is promoted by the learning environment.^e, f	Montessori Services Nienhuis Montessori Shiller Learning
Online-based	The curriculum is delivered to the student through a service subscription contract with an internet-based online curriculum vendor. Students typically access the digital content through laptop computers, though some students will use tablets or desktop computers. Some online curriculum providers will offer adaptive learning assessments to place children in appropriate ELA and mathematics lessons. Students are encouraged to use the internet to research concepts and engage in the content through their own curiosity. Most current online curriculum providers deliver instruction in an asynchronous learning format.	Instructional activities may include watching video lessons, reading online content, reading print or digital books, or engaging in threaded discussions with other students and teachers through an online Learning Management System (LMS). Learning activities are typically calendared for the students based on the semester guidelines of the school. Levels of instructional support offered to the student varies widely by the online curriculum provider used and the parent/teacher oversight practices of the school. Most current online curriculum providers assess student learning through a combination of online auto-graded assignments and teacher-graded assignments.	Apex Learning Bright Thinker i-Ready K12 Silicon Valley High
Project/Unit-based	Project/Unit-based education identifies a singular theme for the student to study over the duration of a few weeks to a few months. These themes typically originate from the core subject areas of history, science, literature, or the arts. The purpose of Project/Unit-based learning is to allow students to immerse themselves into topics to gain a greater appreciation of the subject content, build relationships from prior learning, and to develop an awareness and appreciation of the interdisciplinary nature of the world around them. Project/Unit-based homeschooling families choose this learning style because of their concerns about how they perceive classroom-based schools as teaching the core subjects in silos.	Students in a family can be grouped across several grade levels while allowing for individualized assignments. Once the theme of the unit is identified, several academic subjects are blended with the common thematic thread. Topics are revisited and reinforced throughout the unit duration and connections are built from prior unit themes. The instructional approach is multidisciplinary and student interest directed. The learning environment is fostered through in-person student experiences gained from visiting historical locations, national parks, or live theater and music events.	Exploration Education Five in a Row In the Hands of a Child Moving Beyond the Page Real World Math
Traditional	The use of the word ‘Traditional’ is not to describe a traditional approach to homeschooling but is instead used to describe the use of curriculum commonly found in traditional classroom-based schools. A Traditional approach to homeschooling is accomplished through the use of well-established, research proven, standards-based, state adopted curriculum for a particular grade level. This homeschooling approach generally requires less planning time by the parent and provides assurance to the parent that students are addressing all of the state standards in their course of study within a singular curriculum. Homeschool students who use a traditional textbook-based curriculum are sometimes said to “practice school at home.”	Curriculum is published by the major K-12 publishers used for classroom instruction. The textbooks and workbooks are designed to follow a standardized scope and sequence. The material presented in the textbooks is expected to be completed and mastered at a particular grade level within a school’s academic semester. Traditional K-12 textbooks are likely to have corresponding teacher’s manuals, answer keys, tests, workbooks, review materials, and suggestions for supplementary materials and enrichment activities.	Explode the Code Glencoe Houghton Mifflin Harcourt McGraw Hill Pearson Prentice Hall Singapore
Unschooling	Unschooling is also referred to as de-schooling or self-directed learning by the child. This homeschooling approach is characterized by the freedom given to the child to decide what to study and how the child would like to learn.^g Unschooling should not be confused with non-schooling, which would be the lack of any educational resources, instructional support, or direction given to the child. Unschooling cannot be characterized by any specific type of curriculum. Although, since the child directs the learning approach, it is possible that any type of curriculum could be used by an unschooled child. The word ‘curriculum’ is an unnatural word to use in the context of describing this educational philosophy as the word may imply formalized structure. However, formal K-12 curriculum, such as mainstream standards-based textbooks and workbooks are often used by Unschooled children, as those children have selected to use textbooks to learn.	Unschooling is driven by the personal interest of the child and the instructional approach that is best suited for the child, as determined by the child. Unschooling is rooted in the belief that children are naturally curious about the world around them, and that they want to learn. The instructional approach is not compartmentalized within subject areas. Learning is often eclectic in nature, with the parents finding locally available materials, books, and environmental resources to direct learning. Although the term Unschooling may imply to some people a hands-off approach to education. On the contrary, Unschooling parents who closely follow this educational philosophy are actively involved in the education of their child. Much experimentation is done in regard to learning opportunities and academic materials, as the parent seeks to understand the interests of the child and how that child can best learn.	By definition, no formalized curriculum is universally used.
Waldorf	Founded by Rudolf Steiner (1861–1925), this educational philosophy in homeschooling is characterized by the parent’s goal of meeting the holistic needs of a child – physical, emotional, cognitive, social, and spiritual.^h At an early age, children learn through free play, arts and crafts, rhythm and movement, games, and nature studies. Older children are taught through creative, artistic, imaginative activities putting an emphasis on the development of their intellectual and conceptualization abilities. This educational philosophy can be characterized by the notable absence of materials commonly used by other homeschooling families, such as the lack of traditional textbooks, computers, television, or any other technology products or resources.	Children are typically taught a long lesson at the start of the day with other smaller instructional periods later in the day. Lessons are organized in units that progress for several weeks. In the early childhood stage (grades K-2), the child explores the environment through physical, creative, and sensory activities. During the middle childhood stage (grades 3–8), the child is encouraged to learn through his/her imaginative and artistic faculties. Academics are taught through creative, artistic, imaginative activities. Adolescent stage (grades 9–12), instructional activities emphasize a sense of responsibility for the world and sensitivity to self and others. Primary sources of reading are commonly used when studying history and literature.	Mercurius Oak Meadow Paper, Scissors, Stone

^aShafer (2007). ^bCooper (2012). ^cPerrin (2004). ^dEdwards (2002, p. 6). ^eCorry (2006). ^fHainstock (1997). ^gMorrison (2007). ^hNordland (2013).

The dataset received from the California Department of Education in June 2018 comprised all private schools between the years 2010 and 2017, including student enrollment data for all classroom-based and homeschool-based private schools. To separate private homeschools from traditional classroom-based private schools, schools were removed from the dataset if their total enrollments exceeded 10 students and/or if enrollment at any given grade level at a school exceeded 3 students. All remaining private schools were assumed to be operating as private homeschooling families in California. The demographic information concerning homeschooled students is not collected in California and was therefore not available.

The CDE organizes all California charter schools by county in a charter school map, grouping them into three categories: independent study, site-based instruction, and combination. Blended learning schools fall into the last of these. It was not possible to determine the enrollment trends of students in blended learning charter schools because many such schools only enroll a portion of their students in a blended learning program, with most following a traditional classroom-based schedule. For this reason, we did not include blended learning schools in our analysis of enrollment trends or student demographics.

Student enrollment and demographic information for all identified nonclassroom-based charter schools was collected from the publicly available Ed-Data website, a partnership between the CDE, EdSource, and the Fiscal Crisis and Management Assistance Team/California Schools Information Services designed to compile and organize comprehensive data about California public schools for the purpose of informing educators, policy makers, the legislature, parents, and the public. The master dataset was analyzed using SPSS Statistics for Windows Version 25.0 (Armonk, NY: IBM). Regression analysis was performed using the R statistical software (version 3.5.1).

Results and discussion

Educational philosophies

Like classroom-based public schools, nonclassroom-based independent study charter schools in California are responsible for ensuring that students meet the state standards for each grade level. Each student is assigned a credentialed teacher charged with monitoring, overseeing, and facilitating learning through periodic meetings with the parents and student. Since the establishment of California charter schools in 1992, independent study charter schools have been allowed a high level of flexibility in determining the curriculum and instructional opportunities for enrolled students, which these schools utilize to create personalized learning plans to meet their different academic needs. Those learning plans are created in a collaboration between the credentialed teacher, parent or guardian, and student. The three independent study charter schools used in this study are closely related to their PSA counterparts because of the high level of parent involvement in the selection of the curricula, learning activities, and daily home instruction with their child. The similarity these public schools have to private homeschools opens up the opportunity to explore a variety of future research questions on this segment of K-12 education through the lens of independent study charter schools.

In this paper, the term educational philosophy, a phrase that is commonly used among independent study teachers and homeschooling parents to provide a general description of their instructional approach to educating a child at home, offers an explanation of the general curriculum, pedagogy, and instructional delivery modality in nonclassroom-based K-12 learning. The educational philosophies followed by parents can be very influential in the development of a personalized learning plan for the child, either at independent study charter schools or in private homeschool settings. Table 1 describes the distinguishing characteristics, instructional approaches, and commonly used curricula for each educational philosophy.

However, regardless of the educational philosophy of the parent, it is the responsibility of the independent study charter school to ensure that each child is learning at the appropriate grade level, following the state standards for public school students, and working toward meeting or exceeding the requirements of state assessments. Credentialed teachers at independent study charter schools are charged with identifying any missing content standards in non-traditional curricula used by students as well as for assigning supplemental curricula, as necessary, to fill any instructional gaps. As a result, this added layer of influence may have an effect on distribution of educational philosophies reported at these schools and should be considered when extrapolating these results to the pedagogy and curriculum selection of PSA homeschooling families.

If there is no school-adopted curriculum at an independent study charter school, as is the case with these three nonclassroom-based independent study charter schools, student assessment scores and parent educational philosophies can be the two most significant variables in determining the curriculum of a personalized learning plan. Student learning styles and personality types can also play an important role. The parents of the students enrolled in the three participating schools in this study took an active role in the selection of the curriculum and learning activities used to educate their children, typical of most such parents. Prior to selecting any curriculum, the credentialed teachers at these three schools used the i-Ready® diagnostic assessments for reading and math and the state-mandated California Assessment of Student Performance and Progress results to help identify the particular learning needs of each student. Afterward, the parents and credentialed teachers discussed curriculum options and instructional strategies.

Parents formulate their approach to homeschooling their child based on internet research, including social media, and through conversations with other homeschooling friends and teachers. Many parents may not recognize that they are teaching their child according to a specific homeschooling pedagogy, thus making it challenging for researchers to acquire this information directly from parents. Surveying the teachers, who are trained to identify educational philosophies and learning styles, instead of surveying the parents, allowed for a more accurate and complete picture of the curricula and pedagogy used at the independent study charters schools. In an effort to gain insights on the distribution of instructional practices among students, 309 credentialed teachers from the participating schools were surveyed and asked to use their professional judgment to identify the educational philosophies that best describe the pedagogy for that student. Students remain with their assigned teacher as the student progresses through the grade levels, allowing the teacher to become very familiar with the educational approaches used by each of their students and families.

Traditional philosophy was the most commonly followed primary educational philosophy, representing 57.8% of the students. This philosophy typically features a standards-based curriculum that is also commonly used in classroom-based public schools. As independent study charter schools in California are also public schools and must follow the adopted state content standards, this is not surprising. We also expect this percentage to be higher than what is practiced with PSA families. Multiple studies have documented the fact that, when parents first homeschool their children, they lean toward a more traditional classroom curriculum to teach “school at home” with their children, until they progress to alternative approaches that may be less structured (Bell, Kaplan, & Thurman, 2016; Gann & Carpenter, 2019; Gray & Riley, 2013; Kraftl, 2013). For this reason, results should be interpreted as a snapshot in time for a particular population of students and families and suggest these educational philosophies may change for any given family, as the family and student evolve in their home education experiences.

Classical was the second most common primary educational philosophy, with 10.8% of the students using classic literature in a formalized curriculum in well-defined stages of grammar, logic, and rhetoric. The Classical approach to education is unique in that the study of Latin is woven throughout the stages of a child’s education, ranging from grammar charts in the initial learning levels and Latin composition at the high school level (Hahn, 2012). Further, as defined by Perrin (2004), a classical approach is both authoritative and enduring, “begun by the Greeks and Romans, developed through history and now being renewed and recovered in the 21st century” (p. 6).

The project/unit-based educational philosophy was identified with 9% of the students and is described as thematic and interdisciplinary in its instructional approach. Projects often revolve around STEM (science, technology, engineering, and mathematics), with parents participating in open-ended, creative ways to promote a child’s interest (Bachman & Dierking, 2011). Only 4.8% of the students were primarily taught online for all of the core subjects, although instructional funds can be used to acquire technology for all students. Online learning is more of an instructional delivery modality than it is an educational philosophy but was included in the survey to capture the students/families who prefer the use of online resources to achieve academic core content standards. Reasons for choosing an online approach to education can vary from easy access to high quality virtual curriculum to an engaging and personalized curriculum (Pell, 2018). However, with such a small percentage of students primarily learning through online resources, California independent study charter schools such as those described in this research could not be appropriately described as cyberschools, eSchools, or virtual charter schools.

The fifth most common educational philosophy was Unschooling, utilized by a reported 4.7% of all students. Within this unregimented approach to education, there are variations in the degree of structure amongst families found in either the educational content or the learning process (Neuman & Guterman, 2017). A formal curriculum is not typically utilized under this educational philosophy. Unschooling can further be described as either “relaxed homeschooling” or as being completely child-led and created (Gray & Riley, 2013, p. 8).

The Charlotte Mason, Waldorf, Delayed Academic Approach, and Montessori educational philosophies represented less than 2% of the students. In total, all the educational philosophies discussed in this paper represent 92.5% of the students, with only 7.5% of the teachers selecting the Unknown/Other category.

The percent distribution of educational philosophies changed when the teachers were given the option to select more than one educational philosophy, indicating that 73.7% of all students used some type of Traditional standards-based classroom curriculum. This increase from 58.7% using Traditional as the primary philosophy may reflect the common practice of using standards-based curricula to fill any instructional gaps in non-traditional K-12 education. For example, a student following the Montessori curriculum may need to fill in certain missing California content standards. Furthermore, when teachers were given the option of selecting more than one philosophy, the Online-Based learning modality increased to 14.1%, from 4.8% as the primary. This may likely be attributed to students utilizing online content for some but not all of their instruction.

Even though, in many ways, the active parent involvement curriculum selection and home instruction by parents at California independent study charter schools described in this paper are similar to the private homeschooled students through a PSA, the idea that this distribution of educational philosophies is also reflective of the educational philosophies of parents who privately homeschool their children cannot be generalized. We speculate that the former may be less inclined to follow the Traditional educational philosophy because such students are not required to adhere to the California content standards and do not participate in any annual summative state assessments. However, the broad geographic distribution of the students in this study (Figure 1) and the large sample size of 5,511 students, comprising 4.8% of all California independent study charter school students in 2016, suggest that these results are representative of the independent study, nonclassroom-based charter schools throughout California.

Enrollment trends

As we transition from the pandemic to the endemic phase of Covid-19, the disruption to traditional norms of classroom-based K-12 education may result in a shift in the way parents perceive their educational options for their children, which may cause more families to choose nonclassroom-based educational options for their children. Several studies have investigated the reasons that parents choose to homeschool their children (Boschee & Boschee, 2011; Green & Hoover-Dempsey, 2007) but quantifying enrollment for these nonclassroom-based students has been more challenging, due in part to varying reporting requirements of each state (Isenberg, 2007). In California, the reporting requirements for PSA and independent study charter school students are well established. In this study, we sought to examine the historical, pre-pandemic enrollment trends for nonclassroom-based enrollment in California and make comparisons to national enrollment trends during the same period.

According to a recently published report from the U.S. Department of Education, in 2016, an estimated 3.3% of all school-aged children were homeschooled in the United States (Snyder et al., 2019). The department first began collecting these data in 1999, when it indicated that 1.7% of students were homeschooled (Table 2). A well-correlated, positive linear regression (R² = 0.901) was found when the percent of homeschooled students was plotted against year (Figure 2). Assuming this linear trend continues, a regression model was used to estimate the percent of homeschooled children in the United States in 2020, 2023, and 2025 (Table 2). It is projected that 4.1% of the national K-12 student population in the United States will be homeschooled in 2020, increasing to approximately 4.6% by 2025.

Figure 2. Linear regression correlation of the estimated percentage of school-aged children educated at home in the United States.

Table 2. Predicted estimates of the percentage of school-aged children who will be homeschooled in the US in 2020, 2023 and 2025, based on the US department of education parent survey results from 1999 through 2016.

Estimated Percentage of Students Homeschooled in the US
Measurement	Year	% HomeSchooled Value	% HomeSchooled Trendline Value	95% Confidence Interval of Trendline
Actual	1999	1.7	1.8	1.5–2.2
Actual	2003	2.2	2.3	2.0–2.5
Actual	2007	2.9	2.7	2.5–2.9
Actual	2012	3.4	3.2	3.0–3.4
Actual	2016	3.3	3.6	3.5–3.8
Predicted	2020	4.1	4.1	3.8–4.2
Predicted	2023	4.4	4.4	4.2–4.6
Predicted	2025	4.6	4.6	4.3–4.8

In light of these nationally reported trends, we have summarized the enrollment trends for nonclassroom-based schools in California, the most populous state. The CDE collects student enrollment data for all public and private schools, so, in California, it is possible to accurately determine the percentages of students being educated in nonclassroom-based schools for any given year, rather than relying on survey estimates, as is the case when examining broader, national trends. In this paper, nonclassroom-based enrollment trends were evaluated for California private homeschools (PSA) and California public independent study charter schools.

The enrollment data for years 2010 through 2017 are reported in Table 3. Linear regression models were used to project student enrollment through 2025 for the various categories of California public and private schools (Figure 3). Total private school enrollment was variable each year, resulting in a weak model prediction of declining enrollment (R² = 0.369). The private school enrollment data were sorted into two groups: PSA Homeschool and PSA Classroom. Separating the classroom-based private schools from the total private school dataset generated a slightly better linear correlation (R² = 0.572), but the negative sloping regression line suggests declining enrollment in California’s classroom-based private schools. However, when the dataset was filtered to estimate the enrollment of PSA homeschooled students, a strong positive linear relationship was found (R² = 0.911). According to the linear regression model estimates, the number of privately homeschooled students in California is predicted to increase from 28,928 in 2017 to 38,925 students by 2025.

Figure 3. Linear regression correlations for K-12 student enrollment in various types of public and private schools in California.

Table 3. Public and private K-12 student enrollment in California (2010–2017).

Enrollment Summary		Total Student Enrollment in California by School Year								Predicted Enrollment			Model Parameters
School Year		2010	2011	2012	2013	2014	2015	2016	2017	2020	2023	2025	Slope	Intercept	R^2
	PSA: Homeschool	22,581	22,837	23,089	24,330	26,639	28,864	29,188	28,928	33,221	36,644	38,925	1,141	-2,270,973	0.911
	PSA: Classroom	521,529	505,754	488,116	507,607	502,533	495,213	492,492	482,697	474,582	463,085	455,421	-3,832	8,215,920	0.572
	PSA: All Schools	544,110	528,591	511,205	531,937	529,192	524,077	521,680	511,625	507,808	499,734	494,351	-2,691	5,944,470	0.369
	Charter: IS	66,877	73,005	80,017	90,466	96,505	104,745	113,272	125,724	147,489	172,256	188,768	8,256	-16,529,222	0.993
	Charter: Classroom	256,982	296,240	358,457	381,035	417,770	440,235	459,480	477,113	590,137	684,393	747,231	31,419	-62,876,003	0.961
	Charter: All Schools	323,859	369,245	438,474	471,501	514,275	544,980	572,752	602,837	737,626	856,650	935,999	39,675	-79,405,225	0.979
	IS + Homeschool PSA	89,458	95,842	103,106	114,796	123,144	133,609	142,460	154,652	180,711	208,900	227,693	9,396	-18,800,195	0.995
	Public: All Schools	6,192,121	6,217,002	6,220,993	6,226,989	6,236,672	6,235,520	6,226,737	6,228,235	6,250,484	6,263,153	6,271,599	4,223	-2,280,097	0.537
	Ocean Grove	1,156	1,455	1,708	1,842	1,867	1,895	1,977	2,287	2,633	3,030	3,295	132	-264,608	0.896
	Sky Mountain	1,373	1,640	1,749	1,881	2,032	2,219	1,646	1,910	2,220	2,411	2,539	64	-126,435	0.353
School	South Sutter	1,431	1,872	2,090	2,145	2,114	2,112	2,099	2,250	2,548	2,795	2,959	82	-163,452	0.609

Student enrollment in California from 2010 to 2017. Data was analyzed using linear regression models to provide student enrollment projections for 2020, 2023 and 2025.

Total student enrollment in independent study charter schools increased from 66,877 students in 2010 to 125,724 students in 2017. When plotted against year, a well-correlated linear relationship was found (R² = 0.993). In 2017, independent study charter school student enrollment represented 20.9% of the total charter school student enrollment in California, with a reported 125,724 K-12 public school students educated outside a traditional classroom-based school. If enrollment trends continue linearly, California will have an estimated 188,768 public school students enrolled in independent study charter schools by 2025.

Grouping the public independent study charter school enrollment and private homeschool enrollment together, a total of 154,652 students in California were educated outside a purely traditional classroom-based school learning environment in 2017 (Table 3). Using the linear regression model parameters, the total enrollment of such students in California is expected to increase to approximately 227,693 students by 2025 (R² = 0.995). This increase echoes the findings of the U.S. Department of Education that indicate an increase in student enrollment in homeschooling at the national level. Given the growing prominence of this alternative form of public and private school education in the United States, there is a need for thorough academic research on the teaching pedagogy and best practices in nonclassroom-based forms of K-12 education.

Our analysis indicates that California had a reported 2.1% of total private and public school enrollment in 2016 that was classified as nonclassroom-based. According to our enrollment predictions, 3.4% of all K-12 students in California will be educated at home by 2025. It is unknown if these numbers are also representative of other states. However, this study demonstrates that a well-correlated, linear enrollment growth trend of nonclassroom-based education (public and private) in California does correspond with positive linear growth trends reported in the U.S. through national surveys conducted by the U.S. Department of Education (Snyder et al., 2019).

Independent study charter school enrollment represented 20.7% and 20.9% of total statewide charter school enrollment in 2010 and 2017, respectively. A two-sample chi-squared test for equality of proportions with continuity correction was used to determine if the student enrollment in California independent study charter schools was outpacing the total enrollment growth in classroom-based charter schools. The result was χ² = 8.3837, with 1 degree of freedom, corresponding to p = .02033. The 0.2% enrollment increase of independent study charter schools from 2010 to 2017 was determined to be statistically significant, with a 95% confidence interval.

It should be noted that the onset of a global Covid-19 pandemic has caused this linear homeschooling projection to reach an inflection point, with outcomes yet to be determined with enrollment data. As families experienced remote learning with little notice or preparation because of the pandemic, it became apparent that the leading role of a parent in the learning of a child in a homeschooling environment was critical to maintaining the education of the child (Green-Hennessy & Mariotti, 2021; Sssenkusu, Ssempala, & Mitana, 2022). Parents’ concerns regarding safety from Covid-19 for their children within a school setting, along with issues surrounding the educational effects of a year-long, swift change to remote instruction, led to an increase in the number of families viewing homeschooling as a viable option (Duvall, 2021).

Response to the Covid-19 pandemic also resulted in an increased awareness of the need to regularly survey families at the national level, through the Household Pulse Survey, to measure how the virus affected American households, including the number of households being used for educational purposes. The Household Pulse Survey data indicate that the number of homeschool parents increased to five million in fall 2020 (Duvall, 2021). Further, and specific to California, the pending legal policies surrounding childhood vaccinations makes the need to examine this enrollment trend more urgent.

In June 2015, California signed into law SB277, a Senate bill removing the personal belief exemption for required school vaccinations. Committee hearings indicated that California would in this way be denying free public school education to the children of parents wishing to avoid vaccination through such an exemption. For this reason, SB277 was amended to allow California independent study charter schools to enroll students with a personal exemption waiver for vaccines. Based on the enactment of this law, it is plausible that the enrollment rate of students at California independent study charter schools may increase at a greater rate than estimated in this paper. Similarly, if Covid-19 vaccines become required for enrollment in classroom-based schools, some parents who choose not to vaccinate their children will need to select a nonclassroom-based learning option for their children.

In 2020 and 2021, the Covid-19 pandemic effectively forced all K-12 students and parents in the United States to participate in some form of nonclassroom-based learning. At this time, we do not have any data that would indicate how the enrollment of nonclassroom-based schools would change in the post Covid-19 era, although, as mentioned, we surmise that this could be an inflection point for the well-correlated linear growth rates of nonclassroom-based enrollment described in this paper. The practice of educating a child at home has become more normalized within society during the pandemic, forcing students and families to participate in this alternative form of education, a school choice option that they may not have fully recognized, understood, or chosen prior to the Covid-19 pandemic.

Demographic summary of students

Demographics of students enrolled in California independent study charter schools were compiled and summarized in this paper to draw comparisons with the national averages of homeschooled students and to students enrolled in traditional classroom-based schools in California. Demographic information of privately homeschooled students in California was not available because the California Department of Education does not collect student demographics through their PSA application. The 2016 academic year was selected for California student demographic data so that it could be compared to the most recent national demographic data for homeschooled students conducted by the U.S. Department of Education (Snyder et al., 2019). California’s independent study charter schools are included as part of the 6,226,737 total public school students reported for 2016. Likewise, Ocean Grove, Sky Mountain, and South Sutter Charter Schools represent a subset of the 113,272 total students enrolled in independent study charter schools for 2016.

Of the 113,272 independent study charter school students in 2016, 55% were reported as low socioeconomic status (SES), a much higher rate than the 21% reported nationally for homeschooled students. However, it was much closer to the statewide average of 60.5% for all California K-12 public school students (Table 4). The three participating schools in this study reported substantially lower percentages of low SES students, with 18.3%, 25.8%, and 37.4% in Ocean Grove, Sky Mountain, and South Sutter, respectively. This may be partially attributed to the higher income counties served by the participating independent study charter schools, such as Silicon Valley for Ocean Grove and Orange County for Sky Mountain (Figure 1). The enrollment of students in the participating schools was never capped or restricted by any means, such as a lottery system.

Table 4. Student demographics of California K-12 students and homeschooled students in the United States.

2015–2016 Student Demographic Characteristics Collected from the U.S. Department of Education and California Department of Education
	Data: CA Department of Education	Data: U.S. Department of Education	Data: California Department of Education
Characteristic	All CA Public School Students	U.S. Homeschool	CA Independent Study Charter School	Ocean Grove Charter School	Sky Mountain Charter School	South Sutter Charter School
Total Students	6,226,737	1,689,726	113,272	1,977	1,646	2,099
Gender:
Male	3,199,590 (51.4%)	811,068 (48%)	54,627 (48.2%)	990 (50.1%)	807 (49%)	1,015 (48.4%)
Female	3,027,147 (48.6%)	878,658 (52%)	59,195 (52.3%)	987 (49.9%)	839 (51%)	1,084 (51.6%)
Low Socioeconomic Status	3,768,815 (60.5%)	354,842 (21%)	62,255 (55%)	362 (18.3%)	425 (25.8%)	785 (37.4%)
English Language Learner	1,373,724 (22.1%)	270,356 (16%)	7,537 (6.7%)	55 (2.8%)	27 (1.6%)	57 (2.7%)
Students with Disabilities	661,798 (10.6%)	354,843 (21%)	10,788 (9.5%)	175 (8.9%)	94 (5.7%)	179 (8.5%)
Race/Ethnicity
Asian/Pacific Islander	551,229 (8.9%)	50,692 (3%)	3,473 (3.1%)	154 (7.8%)	98 (6%)	64 (3%)
Black, Non-Hispanic	361,752 (5.8%)	135,178 (8%)	8,070 (7.1%)	26 (1.3%)	51 (3.1%)	54 (2.6%)
Hispanic/Latino	3,360,562 (54%)	439,329 (26%)	41,902 (37%)	433 (21.9%)	414 (25.2%)	315 (15%)
White, Non-Hispanic	1,500,932 (24.1%)	996,938 (59%)	47,597 (42%)	1,067 (54%)	862 (52.4%)	1,374 (65.5%)
Other Race/Ethnicity	413,452 (6.6%)	67,589 (4%)	8,746 (7.7%)	194 (9.8%)	131 (8%)	163 (7.8%)
Not Reported	38,810 (0.6%)	N/A	1,284 (1.1%)	102 (5.2%)	90 (5.5%)	129 (6.1%)

In California, 22.1% of all public school students were identified as English language learners in 2016 (Table 4). Statewide, a much lower percentage of independent study charter school students (6.7%) were identified as English language learners. Ocean Grove, Sky Mountain, and South Sutter reported 2.8%, 1.6%, and 2.7%, respectively, of English language learner student enrollment in 2016. We speculate that the substantially lower percentage of English language learners enrolled in California independent study charter schools may reflect the inherent challenges associated with acquiring English language proficiency in a household learning environment where English is likely not the primary language spoken. English language learner students enrolled in the participating schools received in-person, weekly English language tutoring, with a standards-based curriculum and formative assessments in reading occurring periodically throughout the year. The national homeschool estimate of 16% English language learners reported by the U.S. Department of Education should be interpreted with caution because the data were collected through surveys voluntarily completed by parents of K-12 children rather than through any formal English language assessment, such as the English Language Assessments for California (ELPAC).

Generally speaking, California independent study charter schools are less ethnically diverse than the population of K-12 public school students statewide, with an average of 42% of students reported as White, Non-Hispanic, compared to 24.1% for all California public school students in 2016 (Table 4). The ethnic diversity of California may contribute to the findings of fewer White, non-Hispanic homeschooled students than the national average (59%). California independent study charter schools do show a slightly higher percentage of Black, non-Hispanic (7.1%) students compared to the statewide public school average of 5.8%. The demographic makeup of nonclassroom-based students in California does not reflect the statewide student demographic averages, indicating that homeschooling may be gaining ground as a more acceptable form of education within certain ethnicities and communities.

Conclusion

The Covid-19 pandemic has forced most K-12 aged children into a nonclassroom-based learning environment, bringing universal awareness to this alternative form of K-12 education. California independent study charter schools that are structured to involve parents in the selection of curriculum and pedagogy for educating their child at home may help provide researchers a window into educational practices of the less accessible privately homeschooling families. Our research has shown that a traditional approach to learning and the use of common resources found in classrooms accounted for 57.8% of the primary curriculum used by students in these three participating schools, indicating that only 4.8% of parents opt for online curriculum as their main curriculum type. Classical education (11%) and project-based/unit learning (9%) followed in popularity. Emphasis on California Content Standards at the independent study charter schools may skew curricula results more toward traditional standards-based classroom curricula when compared to the homeschooling practices of PSA families who are not required to follow state content standards.

If the U.S. Department of Education estimates are accurate and this sector of education continues to grow in the ways demonstrated in this paper, it is projected that 1 in 22 students, or 4.6% of all school-aged children, will be homeschooled by 2025. In California, children learning outside of a traditional classroom environment have become increasingly more common, representing a reported 2.1% of all public and private school students in 2016. Similar to national enrollment growth trends, California enrollment data showed a well-correlated, positive linear trend for students being educated outside a traditional classroom, with student enrollment in independent study charter schools representing 20.9% of all California charter school students in 2017. We speculate that the growth in homeschooling enrollment over time demonstrated in this paper may currently be at an inflection point as a result of the Covid-19 pandemic that has had the effect of making parents more aware of and familiar with nonclassroom-based learning options for their children.

Independent study charter school student demographic information was collected from public records at the California Department of Education and summarized to indicate a less ethnically diverse population, with the exception of a slight increase in the percentage of Black/Non-Hispanic students (7%) compared to all California public schools (5%). The percentage of low socioeconomic students enrolled in California independent study charter schools (55%) was similar to total student enrollment in California public schools (61%), but substantially higher than the national estimate of 21% for homeschooled students. The inherent challenges associated with home educating an English learner student in a home where English may not be the primary language spoken could contribute to the relatively low percentage of English learner students enrolled in California independent study charter schools (7%) compared to the statewide average of 22%. Demographic information of privately homeschooled K-12 students in California was not available from the California Department of Education.

This analysis indicates that private homeschooling and independent study charter school enrollment will become an increasingly common educational option for families in the future. The enrollment trends described in this paper reveal a societal shift in terms of the growing number of parents seeking nontraditional, nonclassroom-based K-12 learning opportunities for their children. We speculate that the post-Covid-19 era of K-12 education will move to a more nonclassroom-based learning environment, as parents more fully understand alternatives to a traditional classroom learning experience for their child.

The student demographics, enrollment data, and home-based pedagogies described by educational philosophies in this study provide a foundation for those interested in researching this most elusive and least understood sector of education in the United States.

Disclosure statement

No potential conflict of interest was reported by the author(s).