Secondary school students’ misconceptions in genetics: origins and solutions

ABSTRACT

Even though genetics has been implemented in biology curricula at secondary schools for decades, reports repeatedly indicate that students still hold various misconceptions about this topic. To successfully target these misconceptions, we need to know their nature and origin. We aimed to investigate these properties in the Czech educational system among students of lower-secondary education (ISCED 2) and upper secondary education (ISCED 3). Students underwent a test focused on the basic concepts of genetics based on the content of the national curriculum and current textbooks. The results showed that students have general ideas about the nature of genetic information but struggle to synthetise this knowledge into a deeper understanding of functions in the living body. In many cases, these findings resulted in an increase of various misconceptions. Compared with data about the Czech educational environment and its properties, these problems are caused by a disconnection between the rules of inheritance and functions and impacts of DNA (trait development) on multiple levels of biological organisation both in the national curriculum and textbooks. Therefore, in order to prevent misconceptions, we should focus not only on the way lesson are conducted but also on the changes of national educational policies in the Czech Republic.

KEYWORDS:

• Misconceptions
• genetics
• secondary education

Introduction

We live in the genomic era. Many of the current science trends are based on molecular genetics and the term gene has become common in the media for several decades now. Genetics became a part of our daily life in terms of health care, agriculture and technology, but also raised many ethical questions. Therefore, it is essential for students not to see genetic information just as a ‘black box’, but to understand the basic principles of genetics to make informed choices in their lives (Nowgen 2012). Educational systems around the world understood this need, and genetics has become a well-established part of many national curricula, even at the lower secondary level (Kiliç and Saǧlam 2014; Aldahmash and Alshaya 2012; Knippels, Waarlo, and Th. Boersma 2005).

Since the 1980s, various researchers have tried to uncover if education is preparing students well enough for their future with genetics. Many researchers showed that students hold numerous misconceptions about the topic, and they often lack a deeper understanding of genetics (Kinnear 1983; Stewart 1982). Common problems found were confusion of basic terms (like gene, chromosome, allele or meiosis and mitosis) and shallow understanding of their concepts as well as misconceptions about gene expression (how DNA influences cell functions) (Aldahmash and Alshaya 2012; Lewis and Wood-Robinson 1998; Saka et al. 2006). Unfortunately, recent findings suggest that this situation still has not changed (Haskel-Ittah and Yarden 2018; Kiliç and Saǧlam 2014; Vlčková, Kubiatko, and Usak 2016).

One of the main reasons could be that studies often focused more on the flaws in understanding of genetic concepts than an investigation of their origin. Many studies already suggested that students’ misconceptions can be influenced by the national curriculum (Lewis and Wood-Robinson 1998; Osman, BouJaoude, and Hamdan 2017; Knippels, Waarlo, and Th. Boersma 2005), textbooks and teaching methods (Cisterna, Williams, and Merritt 2013; Topçu and Şahin-Pekmez 2009; Saka et al. 2006) or even the media (Donovan and Venville 2012). Other studies have shown that in common educational practice, we struggle to promote systems thinking skills and effective navigation between the levels of biological organisation (Marbach-Ad and Stavy 2000; Knippels, Waarlo, and Th. Boersma 2005), which results in students’ rather fragmentary knowledge (Lewis, Leach, and Wood-Robinson 2000; Lewis and Kattmann 2004). On the other hand, studies scarcely give more specific national recommendations on how to target these problems on various levels of the educational system. This situation makes needed changes in educational policy harder to implement and accomplish.

Formulation of precise and functional recommendations is not trivial because it requires consideration of all aspects of the educational environment in a country. Therefore, our aim was not only to explore understanding of basics of genetics among students of ISCED level 2 and 3 in the Czech Republic, but also to compare the results with the current state of educational practice in our country (namely, the content of the national curriculum, the applied curriculum, and the textbooks). That intention enabled us to suggest more specific changes in the national educational practice that could serve as a potential inspiration for implementation of similar studies in other countries.

Methods

To be able to uncover the most common misconceptions and their impact on understanding of genetics along the spectrum of many schools in the Czech Republic, we prepared a test based on our previous content analysis of current biology textbooks used in secondary schools, alongside the national curriculum requirements (Machová 2021).

The biology teachers of the involved classes were also asked to briefly describe their genetics lessons, namely: the number of lessons devoted to the topic, the content of the applied curriculum, the relationship towards the topic, their education in genetics and where their students mostly struggle to understand the topic.

Testing tool

We used a short didactic test as our testing tool based on the common basics of the national curriculum for both lower secondary education (ISCED 2) and general upper secondary education (ISCED 3) (in detail in Appendix 2) and the common base of textbooks aimed at both levels. Therefore, the test was focused only on understanding the main key principles of heredity and genetics: the central dogma of molecular biology (understanding of trait development), the functions of DNA, the impact of asexual and sexual reproduction on heredity, and the application of genetics in real life situations.

The test consisted of 10 problem tasks – eight were newly prepared and two were adopted from a collection of TIMSS 8th-Grade Science Concepts and Science Items from 2011 (IEA 2013). (The translated version of the whole test is included in Appendix 1). The content validity of the tool was determined by two experts in the field of genetics and molecular biology and two experts in biology education. The tool was then beta-tested by the group of 30 first-year bachelor students in the Faculty of Education (Charles University) and 10 students in 8th grade at a lower secondary village-school in north Bohemia. The test and testing procedure were then updated to ensure that students understand all the tasks given and the time limit is sufficient.

The test was a combination of open, semi-open and multiple-choice tasks, so the students often had to provide a written explanation for their answers (e.g. Do all the cells in our body have the same genetic information? Yes or no – explain your answer.). Answers to open and semi-open tasks were rated as correct only in those cases where the student chose the correct answer and gave the correct explanation for it. Every task was rated by one point (total test – min. 0 and max. 10 points) and no points were subtracted if the answer was wrong.

To identify existing misconceptions, written answers were then categorised by an open-coding system according to their main idea into several types (different in every question). If any pattern was visible, wrong answers were categorised as well as the correct ones.

Sample

Respondents were students of general education divided into two groups according to their educational level – ISCED 2 and ISCED 3. Altogether over 1300 state and private schools in the Czech Republic were asked to participate in the research, but only a few were willing to.

The first group (ISCED 2, N = 605) studied genetics for the first time during their compulsory school attendance and consists of students of 8th and 9th grade from 21 lower secondary schools in different locations all around the Czech Republic (small and big schools from cities as well as rural areas).

The second group (ISCED 3, N = 303) were students of gymnasiums, which are schools offering general education for only selected numbers of chosen students that are expected to continue their education at tertiary level. These schools offer upper secondary education (ISCED 3) or a combination of lower and upper secondary education (ISCED 2 and 3) in one longer programme. In this study we included students from 10 gymnasiums that, regardless of the total length of their study program, already reached ISCED level 3 (grade 10th to 13th).

Gymnasiums mostly enrol talented individuals and enthusiastic scholars; therefore, these schools gain much better results in international tests (e.g. PISA) than other schools at the same educational level (Straková 2009). Other types of upper secondary schools (high schools) are also present in the Czech Republic but were not included in the study because many of their study programmes omit biology or shorten its curriculum. As the students of gymnasiums are only a selected part of the population of ISCED 3 students, our ambition was not to statistically compare ISCED 2 and ISCED 3 groups.

Testing tool administration

The participating students were tested during the school year 2018/2019 in a window of 1–4 weeks after their lectures on genetics and molecular biology were finished. This allowed us to see a direct impact of the lessons on the students’ understanding. Biology teachers of involved classes were given the instructions and administered the test themselves.

Results

The test scores gained by ISCED 2 students reached a mean of 2.7 points and at ISCED 3 a mean of 4.8 points (see Figure 1). However, in both groups, only a small number of students were able to pass most of the tasks.

Figure 1. Students’ overall score in the test. Students at ISCED 2 are visualised in the light shade, ISCED 3 in the dark shade. Maximum score was 10.

Most common misconceptions found among the answers to semi-open and open questions were very similar between both ISCED 2 and ISCED 3 students.

In semi-open tasks, many students were able to choose the correct answer but were not able to give any or correct explanation. Many of them, on the other hand, directly stated that the reason for their restraint was that they simply did not know. Also, students often needed less time than was given, so the time available was not a limitation. The number of students not stating any explanation is mentioned for all tasks below.

In TASK 1 (see Table 1), students should simply explain the nature of genetic information to the unknowing person. In many cases, students struggled to explain genetic information of a more complex nature and omitted important information. The most common correct answer was that genetic information is a body-manual inherited from parents.

Table 1. Overall results and rate of detected misconceptions and their types in TASK 1.

Question 1: Nature of genetic information
Not know/no answer		Most common misconceptions	Occurrence of misconceptions
ISCED 2 (%)	ISCED 3 (%)		ISCED 2 (%)	ISCED 3 (%)
28.1	8.6	Wrong understanding of the basic terms	7.1	9.2
Correct answer		Attributing wrong functions to DNA	6.3	8.3
ISCED 2 (%)	ISCED 3 (%)	Wrong concept of heredity	4.5	4.3
15.0	50.8	Mistook genetic information for genetics	5.5	0.7

Students often tended to use basic genetic terms in the wrong context. Instead of explaining the meaning of the term genetic information, ISCED 2 students often started explaining genetics as a science studying heredity and variability of organisms. Students in both groups also showed a wrong concept of heredity. For example, they stated that genetic information is transmitted from various relatives (not just mother/father), carries traits instead of predispositions for them, as well as accommodating horizontal transmission of genetic information.

It was also revealed that students attributed many higher functions to genetic information (for example its direct impact on behaviour and thinking) or simplified its role to the point where ‘genetics information is used to pick our eye colour’.

TASK 2 (see Table 2) was semi-open. Students had to choose how similar is genetic information of Paramecium and its offspring in case of simple cell division and reason their answer. Paramecium was chosen as it is mostly used as model organism in biology education in the Czech Republic.

Table 2. Overall results and rate of detected misconceptions and their types in TASK 2.

Question 2: Cell division of Paramecium
Not know/no answer		Most common misconceptions	Occurrence of misconceptions
ISCED 2 (%)	ISCED 3 (%)		ISCED 2 (%)	ISCED 3 (%)
51.9	27.7	Genetic information only splits	9.3	7.9
Correct answer		Wrong concept of heredity	7.9	5.3
ISCED 2 (%)	ISCED 3 (%)	All single cellular organisms are the same	3.3	4.0
12.4	41.6

The response rate at both levels was rather low. Students mostly failed to understand that cell division is not only a simple split of the cell and that genetic information needs to be copied before the division. Again, many students revealed problematic concepts of heredity. They believed that two daughter cells, originated from a cell division, cannot have the very same genetic information or that such cells have to share only a small proportion of genetic information to be related. Some students also hold a belief that all Parameciums (or all single-cellular organisms) look the same or that they are so simple they necessarily have identical genetic information.

TASK 3 (see Table 3) was closed multiple-choice with four options (only one correct). Students were given problem task about neuron cells – they got the information that adult neurons do not undergo the cell division and were asked if these cells in this case still have genetic information or not.

Table 3. Overall results and rate of detected misconceptions and their types in TASK 3.

Question 3: Genetic information of neuron cell
Not know/no answer		Most common misconceptions	Occurrence of misconceptions
ISCED 2 (%)	ISCED 3 (%)		ISCED 2 (%)	ISCED 3 (%)
2.6	1.7	Neurons do not need genetic information, they get information from the surrounding cells	25.8	18.8
Correct answer
ISCED 2 (%)	ISCED 3 (%)	Non-dividing cells do not use genetic information	15.0	14.9
44.6	56.1	Neuron cells do not have any genetic information	11.9	8.3

Only on rare occasions, students did not state any answer. Around half of them chose the correct answer that the cell cannot normally function without genetic information. The most chosen distractor was a statement that neurons receive information from neighbouring cells. Many students also hold a belief that genetic information is not needed in the case when the organism does not reproduce itself.

In the following tasks, the overall occurrence of misconceptions was low or there was a visible pattern of only one or two major types of misconceptions. Overall results for TASK 4–8 are shown only shortly in Table 4.

Table 4. Overall results and rate of detected misconceptions in TASK 4–8.

Task	Correct answer (%)		Not know/no answer (%)		Misconceptions total (%)
	ISCED 2	ISCED 3	ISCED 2	ISCED 3	ISCED 2	ISCED 3
4. cell differentiation	11.7	31.7	53.6	36.0	18.8	19.1
5. nucleus functions	52.6	79.2	38.2	12.5	5.0	3.3
6. DNA functions	2.5	10.6	63.8	47.9	7.3	14.9
7. DNA vs protein	9.3	42.9	68.1	29.7	7.9	16.2
8. use of genetics	1.7	16.5	32.4	7.9	8.6	10.2

TASK 4 was semi-open, students were reminded that there are different cells in their body with many different functions (e.g. muscle, bone cell, blood cell) and asked if all the cells in their body have the same genetic information. Students in both groups were quite creative stating various reasons for their answers (for example that all cells in the body come from one zygote, or that if one body were to have more than one set of genetic information, police could not use genetic-based evidence). Still, many students did not state any explanation at all or stated that they did not know – notable 53.6% at ISCED 2.

The most common misconception was a statement that different functions of cells need to be secured by differences in their genetic information. This misconception occurred in 13.5% of ISCED 2 and in 15.2% of ISCED 3 students. Some students also mentioned different origins of genetic information (half from mother/father), which apparently makes them think there can be at least two types of cells in the body (though only around two 2% of all students stated this).

TASK 5 was an open task, in which students had to explain the role of the cell nucleus, although even this simple question stayed unanswered by many. The amount of all types of detected misconceptions was low in both groups. Detected misconceptions contained statements like the nucleus is a decision-making organ of the cell or comparisons of the nucleus to the human brain and the heart. As the most common answer was that the nucleus has a governing function, it can be expected that similar misconceptions may be much more widespread.

Semi-open TASK 6 and TASK 7 were similarly pointing to the long-term role of the genetic information in the process of protein synthesis. Students should explain if and why organisms need genetic information during their whole life, and then according to the short description of DNA and protein, state if these are similar in any way and explain why. The aim of the second question was to give a chance even to a student, who did not yet hear about protein synthesis, to figure out the connection by themselves from the description.

Unfortunately, in both tasks the success rate was low. Specifically, students at ISCED 2 level struggle to give any explanation to their answers (more than 60% in both tasks). Therefore, due to lack of written answers, it was hard to even detect any misconceptions. In TASK 7, though, students showed that knowing the correct answer does not mean correct understanding of the protein’s functions in the body. The success rate for ISCED 2 was 9.3%, but only 2.5% of students stated that DNA is made from proteins, or that proteins are directly created from the DNA molecule. At the ISCED 3 level, the number of students with these statements rose to 15.2%, though the success rate was 42.9%.

TASK 8 was open-ended. Students had to name and shortly describe at least three different ways where knowledge of heredity/genetics is used in real life situations. Students mostly failed, because they gave less than three examples, though the majority stated at least one.

The question showed that students tend to see genetics even in the processes where it is not needed, while on the other hand, they often forgot about the important usage of genetics. For example, they mentioned use of fingerprints during investigation (3.6% for ISCED 2 and 1.3% for ISCED 3), in vitro fertilisation, rarely even detecting a blood group as procedures directly involving genetics knowledge. Notably, in vitro fertilisation is mentioned even in biology textbooks, but except for the diagnostics of hereditary diseases, knowledge of genetics is not needed in the process itself, and students usually mention diagnostics of diseases separately. They also showed very poor understanding of how genetics is used in scientific research (often stating just ‘used in labs’ or ‘by scientists’ without any explanation, occurring in 11.6% for ISCED 2 and 10.5% for ISCED 3).

Results of TASK 9 and 10 were evaluated according to the TIMSS manual (IEA 2013). Overall success rate is shown in Table 5.

Table 5. Overall results and rate of detected misconceptions in TASK 9 and 10.

Task	Correct answer (%)		Not know/no answer (%)		Misconceptions total (%)
	ISCED 2	ISCED 3	ISCED 2	ISCED 3	ISCED 2	ISCED 3
9. TIMSS – kidneys	28.9	59.1	38.5	14.2	5.0	4.0
10. TIMSS – twins	87.3	96.4	0.7	0.0	11.7	3.6

TASK 9 was open-ended, giving students a problem situation, where a father accidentally lost a kidney asking how many kidneys his newborn son will have and why. Students mostly answered correctly that a baby will have two kidneys (in rare cases stated three), but again failed to give a correct or any explanation. Some students also hold a belief that number of organs has nothing to do with heredity – 2.5% among ISCED 2 and 3.3% among ISCED 3 group.

TASK 10 was multiple choice with 4 options with only one correct answer. This question was built on human genetics, where the mother has twins – boy and girl – and students had to decide if their genetic information came from both parents or only from one. This question proved to be the simplest one for the students of both groups. Still, the failure rate at ISCED level 2 was quite high. The most popular distractor in both groups was that while the boy carries only his fathers’ information, the girl only her mothers’.

Finally, to sum up the results of the teachers’ descriptions of how the lesson on genetics were conducted, few key points were found. Firstly, the number of lessons devoted to genetics differs highly between the ISCED 2 and ISCED 3 level. The number of teaching hours for ISCED 2 was 2–8 (mean = 4; SD = 1.9) and for ISCED 3 was 5–60 h (mean = 24; SD = 15.3). Half of the teachers from both types of schools also expressed that they did not have enough time to teach the topic.

Genetics was stated as one of the most complicated topics for their students by 70% of all teachers. One third of them stated the processes of meiosis, mitosis and protein synthesis as the most difficult knowledge to understand for their students, but some also added Mendelian genetics (Punnet squares and allelic interactions). The description of topics covered in the lessons then showed that lessons on genetics very often contain Mendelian genetics even at the lower secondary level (either directly Mendelian laws or simply explained allelic interactions).

On the other hand, the vast majority of the teachers were educated in genetics at university level and have an either neutral or mostly positive relationship towards the topic. They also find knowledge of genetics as mostly very applicable and connected to real life.

Discussion

Czech students of both ISCED 2 and 3 levels showed rather low level understanding of the importance of genetic information. They can simply describe its nature and responsibility for visible traits like students in other countries (Lewis, Leach, and Wood-Robinson 2000; Duncan and Reiser 2007). On the other hand, these students mostly lacked any deeper understanding of how DNA is translated into visible traits (i.e. process of protein synthesis) with the result that they are incapable of understanding lifelong functions of DNA in the living body. The same problem was already detected among students in Israel, Turkey and Germany (Saka et al. 2006; Marbach-Ad and Stavy 2000; Lewis and Kattmann 2004), and also in the USA (Duncan and Reiser 2007), and confirmed in another study in the Czech Republic (Vlčková, Kubiatko, and Usak 2016).

The test showed that this shallow understanding is a fertile ground for various misconceptions that Czech students partly share with their foreign counterparts (Osman et al. 2017; Saka et al. 2006; Chattopadhyay 2005; Lewis and Kattmann 2004). Czech students assumed that different functions of the cell require different DNA, which clearly showed a missing or poorly understood concept of genetic expression; this is also a very common belief among students in other countries (Chattopadhyay 2005; Aldahmash and Alshaya 2012). The Czech students also confused basic terms (gene, DNA, chromosome, etc.), which is a common problem all around the world (Saka et al. 2006; Kibuka-Sebitosi 2007; Kiliç and Saǧlam 2014).

Our results exposed even some more unusual misunderstandings. For example, ISCED 2 students mistook genetic information for genetics. This can be caused simply by either lack of patience with written instructions or their focus on the word ‘genetic’ that instantly triggered the idea of definition of genetics as a science. As it is usually the first thing taught during the lessons on genetics, they could find the term more familiar. Another interesting finding was that students mistook genetic information for signals at the neuronal axons. This finding could be again pointing out a shallow understanding of the role of DNA in the cell. Students often explained nucleus and its content as a governing unit, therefore they can easily believe that it will be possible to replace the nucleus by other surrounding cells that would send orders to mediate the required behaviour of the neuron cell.

Although students of ISCED 3 seemed to demonstrate better results than students of ISCED 2 level, we need to consider that ISCED 3 schools from our study are attended mostly by selected high achieving students who more often continue to universities, and their higher mean success rate in didactic tests is a well-known phenomenon in the Czech educational system (Straková 2009). On the other hand, both groups exhibited a similar quantity of detected misconceptions. This finding points to the prevelance of certain misconceptions that can emerge very early and are not influenced during further educational process (Saka et al. 2006; Briggs et al. 2016).

The overall success rate of students was at both levels also highly influenced by their willingness to explain their answers. In many cases, they simply added that they really had no idea how to explain the problem. The results of TIMSS showed that throughout the years, students’ inability to deal with problem tasks and reason answers is caused by a lack of problem-oriented tasks in Czech educational practice rather than laziness of students (Mandíková and Tomášek 2017). This was mainly visible in TASK 6 where over 70% of ISCED 2 students and 88% of ISCED 3 students chose correctly that an organism could not live for a long time without its genetic information, but most students failed to give any explanation. Therefore, the total amount of misconceptions in the population may be much higher, as it was impossible to detect them due to missing written answers.

However, students failed too often even in simple questions addressing common educational goals of the Czech national biology curriculum. Many students were not able to give simple examples of the use of genetics in real life (TASK 7), which is a main goal of the common national biology curriculum at both ISCED 2 and 3 levels (VÚP 2007; NÚV 2017).

The Czech national biology curriculum for ISCED levels 2 and 3 sets very simple but also intentionally rather vague educational goals (NÚV 2017; VÚP 2007) (see Appendix 2 for details) to enable schools to gain more independence while creating their own school curricula. On the other hand, our study showed that teachers at both levels often tended to highly extend the content of the applied school curriculum (adding Mendelian genetics, cloning, detailed structure of DNA/chromosomes, etc.).

This extension can easily mean the key concepts are rushed through, particularly at the ISCED 2 level where only a few lessons are devoted to the basics of genetics. According to biology teachers of ISCED 2 involved in the research, the number of lessons devoted to the topics of genetics ranged from 2 to 8 (mean = 4). Notably, some teachers even refused to participate in the research because they were not able to teach genetics at all due to the lack of time. The same problem is expected also at ISCED 3 level because teachers introduce genetics very often in the last school year (Janštová and Jáč 2015).

The applied curriculum of lower secondary schools was also very much inspired by the content of Czech biology textbooks (Machová 2021). The school curricula also use the same approach to topic ordering during the school years as do the textbooks (Ibáñez Orcajo and Martínez Aznar 2005; Machová 2021). As well as in textbooks, teachers introduced most of the genetics during 8th grade (sometimes 9th grade) with only a brief introduction during 6th grade alongside the topics of the cell and its organelles. This arrangement creates an unnecessary time gap and forces students to learn such abstract topics as cell biology at a very young age. The wrong order of topics in biology textbooks was also found in the Netherlands, possibly causing similar problems (Knippels, Waarlo, and Th. Boersma 2005).

It was already shown that promotion of deep understanding of genetics requires explicit connections among traits, proteins and DNA (Haskel-Ittah and Yarden 2017) at all the levels of biological organisation (Knippels, Waarlo, and Th. Boersma 2005; Duncan and Reiser 2007), but neither the curriculum nor the textbooks for ISCED 2 level promote this (Machová 2021; Janštová and Jáč 2015). The majority of Czech textbooks for ISCED 2 introduce functions of proteins very briefly, mostly in the chapters about human nutrition and never in the chapter about genetics. DNA is mostly introduced as a molecule responsible for hereditary traits, but seldomly as an instruction for proteins (Machová 2021). The same was found for the general upper secondary textbooks used in the USA (Duncan and Reiser 2007). Though the basics of genetics are mostly taught already in 8th grade, characteristics of proteins are often introduced in more details in chemistry textbooks aimed for the 9th grade. Being unaware of the nature of proteins and how they influence the traits, students cannot fully understand genetics (Haskel-Ittah and Yarden 2017; Duncan and Reiser 2007) as the results of TASK 7 showed. This finding also explains why students attributed regulating functions to the nucleus and not to the DNA or proteins (Machová 2021).

The currently used biology textbooks also do not sufficiently connect genetics with reproduction, mainly at cellular level (Machová 2021), which only strengthens the isolation of the concept of heredity (Strand and Boes 2019). As a result, the majority of Czech students showed an understanding for the division of genetic information during sexual reproduction (TASK 10), but on the other hand tend to forget about the importance of DNA in asexual reproduction (TASK 2).

To sum it up, students at ISCED level 2 do not have enough time to understand the basic principles of genetics and they also struggle to gain any meaningful and coherent understanding of the underlying mechanisms of heredity because all the individual concepts needed to do so are taught as separate topics and are unrelated.

On the other hand, the national curriculum at ISCED level 3 already requires an introduction of such advanced topics as population genetics (VÚP 2007). This, though, cannot be successfully done if students still struggle to understand basic principles of heredity and genetics as this research has shown. Even a higher number of genetic lessons at gymnasiums (ISCED 3 level), which ranges from 5 to 60 (mean = 24), did not seem to help students overcome their previous problems with their understanding. The most probable reason is again the too broad applied curriculum with many new terms with no connections to the low level of understanding that students have from the previous educational level.

The rise of various misconceptions is then very understandable in the situation introduced above. Students are trying to create some connections and background for all the new information learned in the class (Wandersee 1986), but failing to connect the new knowledge correctly, which was confirmed also by Vlčková, Kubiatko, and Usak (2016). The prevailing transmissive way of teaching that is common in Czech schools is not helpful either (Zatloukal et al. 2019). Czech students have also only limited opportunities to apply new knowledge during their educational experiences (Mandíková and Tomášek 2017), which then results in very shallow understanding and inability to develop a broader systems thinking needed in topics like genetics (or ecology and evolution) (Gilissen, Knippels, and Van Joolingen 2020).

Applications for practice

In our study, we have uncovered several flaws in the Czech educational system. Improving them can help us to reach more effective learning and teaching experiences that will diminish the misconceptions of Czech students in the topic of genetics.

At first, the national science curriculum should better specify the learning goals and focus more on basic principles of each segment of biology – in the case of genetics this main principle should be both the principle of heredity as well as the central dogma of molecular biology, more specifically understanding the process of trait development. The rest of the curriculum should be built upon these principles (with respect to the given learning goals), so the educators will have a meaningful base that they can begin with while creating the individual school curricula. This approach will also help teachers to select more easily the knowledge and activities needed to reach the learning goals. Teachers should introduce only as many new terms as is essentially needed to reach the understanding of the main concepts, and to not present students with new knowledge, like introducing Mendelian genetics in detail at ISCED 2 level.

The process of protein synthesis should be simplified at the lower secondary level. All parts should be succinctly and clearly introduced and easily visualised. Nonetheless, it should be always introduced to students when they first meet with topics of genetics and heredity. The process of trait development is better explained in a more deterministic way as DNA-protein-trait sequence at this educational level. This approach also requires teaching about proteins and their functions naturally along with the basics of genetics (Duncan and Reiser 2007), not as isolated knowledge of organic chemistry (Gericke and Wahlberg 2013). With the help of the teacher, students should be able to understand the process of inheritance of DNA, DNA as a code for proteins, visualise common proteins' functions in the body, and come to the realisation of how proteins influence physical traits (Duncan and Reiser 2007).

To promote understanding of the basics of genetics, problem-based and inquiry-based strategies are highly recommended over a transmissive way of teaching (Martínez Aznar and Ibáñez Orcajo 2005; Yilmaz, Tekkaya, and Sungur 2011; Araz and Sungur 2007). Students should learn mainly in an active way through various problem tasks, discussions, experiments and other activities such as working with text or diagrams to support the development of their key competences and basic science literacy (Inagaki 1992). The whole teaching process should also be accompanied by sufficient pictures, videos or model representations with specific examples of various characteristics influenced by genes to make the topic less abstract (Marbach-Ad, Rotbain, and Stavy 2008; Rotbain, Marbach-Ad, and Stavy 2006; Haskel-Ittah and Yarden 2017; Çimer 2012).

As the central dogma of molecular biology is not an easy concept to understand (Briggs et al. 2016), educators at all levels should be aware of the level of cognitive development of their students and also the preconcepts that they may already hold (Haskel-Ittah and Yarden 2018). Many students form their understanding of genetics before the topic is even taught, so teachers need to actively challenge students' previous ideas during the lesson, and reconstruct the connections they established between the basic genetic concepts (Haskel-Ittah and Yarden 2018). It is also important to note that all processes in genetics need to be understood at all the levels of biological organisation (Duncan and Reiser 2007) – namely, at the organism, cellular, and molecular levels – and their interconnections stressed during the lessons as further developed in the Yo-yo strategy proposed by Knippels (2002).

Once students fully understand both the heredity of DNA as a main part of the reproduction process and visualise the connections between DNA and traits, they can move forward to the details of this process as regulative functions of DNA and Mendelian laws of heredity at subsequent upper secondary level. Protein synthesis should also be used as a simple way to explain the impacts of mutations, hereditary diseases, as well as now widely used genetic engineering, so students will fully understand the use of genetics in real life (Lewis and Kattmann 2004). These applications and socio-scientific issues connected with genetics should be approached in a form of problem tasks enabling active learning. Using their understanding of protein synthesis as a mediator of trait development, students should assign parts of the processes to specific levels of biological organisation and explain how certain changes at one level affect the other level (Knippels 2002). Students should be also supported to draw conclusions, for example, how changes in gene expression can affect the growth of a selected genetically modified organism, and what the possible threats and benefits of this process are while being applied in agriculture.

After reconstruction of the curriculum, biology researchers and biology teachers should turn their focus towards the commonly used textbooks. Not only do we need to monitor if the textbooks contain the national curriculum, but also if they use the right ordering of the topics that helps understanding and meaningful learning (Knippels, Waarlo, and Th. Boersma 2005). The basics of cell biology, reproduction and human genetics should not be separated but highly connected during the biology classes as well as in the curriculum and the textbooks (Verhoeff, Waarlo, and Th. Boersma 2008). Therefore, teachers also should be motivated to use a different sequencing of topics to connect the topics more efficiently than those that the current textbooks offer.

We believe that students can understand the process of heredity and transformation of the DNA to visible traits (like hair colour or blood group) to a full extent only if introduced as one undivided unit. Teachers often argue that protein synthesis (as well as genetics itself) is too abstract and hard for students to understand (Knippels, Waarlo, and Th. Boersma 2005). Research has already shown that if well-introduced, this perceived difficulty is no longer the case even at the lower secondary level (Day et al. 2015; Freidenreich, Duncan, and Shea 2011) and not at the upper secondary level (Haskel-Ittah and Yarden 2017). A reasonable simplification and proper connection of all parts of the genetics curriculum at all levels of biological organisation will help students not only develop a coherent understanding of this single topic, but along with that also develop better systems thinking skills, which will enable them to navigate more effectively in real-life problem situations (Knippels and Waarlo 2018; Gilissen, Knippels, and Van Joolingen 2020).

Conclusion

Czech students at ISCED 2 and 3 levels struggled with deeper understanding of genetics and did not reach the common educational goals of the Czech national curriculum. They also hold many misconceptions that are very common among students in many other countries worldwide.

Due to the existing very common transmissive way of teaching, vague curricula, inadequate order of topics in biology textbooks, and lack of time (mainly at ISCED 2 level), Czech educational practice prefers depiction of terms before coherent exploration of basic genetic processes. Both curriculum and textbooks do not stress enough the logical connections among basic concepts, such as as protein synthesis and heredity, and topics related to genetics such as cell biology and reproduction. Therefore, Czech students see genetic information mostly as a ‘magic black box’ that somehow happens to create the traits, helps us reproduce, and keeps us alive, but when asked about the underlying principles, the students mostly give up even the easiest explanation. This also results in their inability to use knowledge they gained to deal with problem situations in their real life.

In the light of these findings, changes in educational policy and practice should focus on the clear establishment of the main principles of genetics in the national curriculum, connections among topics related to genetics both in curricula and textbooks, as well as promotion of systems thinking skills and wider use of active teaching and learning methods that allow students to deepen and use the knowledge and skills once learned.

The problems we face in the educational practice in the Czech Republic do not differ from those in other educational systems around Europe. Therefore, it is possible to consider our recommendations more widely and use our study as future inspiration of how researchers can approach the investigations of students’ misconceptions to directly target specific flaws in educational practice and policies.

Disclosure of potential conflicts of interest

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

Acknowledgments

We would like to heartily thank to all the participating schools and all their teachers that sacrifice their precious free time to make this research possible. This research was supported by PROGRES Q17 grant of the Charles University.

Additional information

Funding

This work was supported by the Charles University [PROGRES Q17].

Appendix

Appendix 1: English translation of the used didactic test.

1. 1/ How would you explain term genetic information to the person unfamiliar with the topic?

2. 2/ Paramecium is a unicellular organism that reproduce via cell division. How much will the genetic information of the mother cell similar to the daughter cell? Choose, and explain:

• absolutely different, because: __________________

• slightly different, because: _____________________

• mostly same, because: ________________________

• absolutely same, because: _____________________

3/ Neurons are cells creating the nerve system of the body (e.g. brain, spinal cord). Adult neurons do not divide (=reproduce). Do neurons have genetic information?

• no, they do not divide, so they do not need it

• no, they receive information from other cells around them

• yes, they cannot exist and function correctly without it

• yes, but because they do not reproduce themselves, they do not use it

4/ Our body is made up from different types of cells with different functions (muscle or bone cells, etc.). Do all the cells in our body have the same genetic information? Choose, and explain:

• yes, because: _________________________________

• no, because: _________________________________

• don’t know

5/ Can an organism exist for longer period after its birth without genetic information? Choose, and explain:

• yes, because: _________________________________

• no, because: __________________________________

6/ DNA (deoxyribonucleic acid) is the main part of the genetic information. Protein is a type of complex chemical compound that helps build structures in the body (muscles, hair, etc.). Is there anything these two have in common?

Choose and explain:

• yes, because: ________________________________

• no, because: _________________________________

• not sure, because: ____________________________

1. 7/ Where is knowledge of genetics used in real life situations or industries? Give three or more examples:

2. 8/ Kidneys are organs found in the human body. When he was young, a man had one of his two kidneys removed because it was diseased. He now has a son. How many kidneys his son has?

3. 9/ Twins are born. One is a boy and one is a girl. Which statement is correct about their genetic makeup?

• The boy and the girl inherit genetic material from the father only.

• The boy and girl inherit genetic material from the mother only.

• The boy and girl inherit genetic material from both parents.

• The boy inherits genetic material from the father only and the girl inherits it from the mother only.

Appendix 2: Common educational goals of Czech national curriculum at lower-secondary education (ISCED 2) and upper secondary education (ISCED 3) levels for the topic of genetics.

Common goals for genetic education at ISCED 2 level (NÚV 2017):

• students explain principle of sexual and asexual reproduction and its significance in the light of heredity

• students state examples of heredity in real life and examples of how environment influence the formation of organisms

Common goals at ISCED level 3 (VÚP 2007):

• students use their knowledge of genetic principles to understand the diversity of organisms

• students analyse possibilities of use knowledge of genetics in real life