Analysis of conceptual understanding of solutions and titration among Rwandan secondary school students

Abstract

This study aimed to examine the effect of three teaching approaches: The traditional teaching method, Teacher based demonstration experiment (TBDE), and the Student hands-on experiment (SHE), on students’ conceptual understanding of solutions and titration. The data were collected using a chemistry achievement test (CAT) comprising of 30 multiple-choice questions, prepared according to four levels of Bloom’s taxonomy, including remembering, understanding, applying, and analyzing. The results reveal that TTM alone could help students attain conceptual understanding in the lower-level knowledge domain and showed a slight improvement in the application and analysis level. At the same time, a great misconception was observed in the level of understanding. On the other hand, the combination of TTM with laboratory experiments either by TBDE or SHE improved students’ conceptual understanding of the first three learning domains better than TTM alone. Supplementation of laboratory experiments also improved students’ percentage scores for questions that looked difficult before intervention. The current study recommends that chemistry teachers should combine TTM with a laboratory experiment to bridge the gap between theory and practice. However, despite the positive impact of laboratory experiments in the first three learning domains, their effectiveness seemed to be reduced at the level of analysis. This finding is because the level of inquiry was low. After all, students had to follow the experiment protocol prepared by the teacher. Therefore, we recommend further studies to explore the effect of inquiry-based learning laboratories on students’ conceptual understanding of solutions and titration.

Keywords:

• Bloom’s taxonomy
• conceptual understanding
• TBDE
• TTM
• SHE
• solutions and titration

REVIEWING EDITOR:

• Colby Tofel-Grehl, School of Teacher Education and Leadership, Utah State University, Logan, USA

SUBJECT:

• Chemistry
• Material Science
• Secondary Education

1. Introduction

Acid-base titration and oxidation-reduction (redox) titration are essential topics in chemistry. Oxidation-reduction is a vital chemistry concept because it is the basis of numerous biological and chemical processes. Examples of redox reactions include photosynthesis, electrochemical cell processes, and numerous processes in the human body, including Adenosine tri-phosphate (ATP) creation. However, studies have shown that teaching and learning about redox in secondary chemistry courses can be challenging (Österlund et al., 2010). Students struggle to recognize redox reactions, assign oxidation values, and balance redox reaction equations, and teachers find it challenging to explain the mechanism of redox reactions. Most of these difficulties are caused by the molecular models defining the redox processes (Brandriet & Bretz, 2014). Acid-base chemistry is also an important topic in chemistry since it aids in the explanation of phenomena seen in the natural world (McClary & Bretz, 2012). Several other chemistry concepts, including chemical equilibrium, redox reactions, and solutions, are closely related to acids and bases. A good foundation of understanding acid-base concepts is crucial for secondary students.

Nevertheless, despite the significance of this subject, research has revealed that students still struggle with it (Kala et al., 2013). There are three degrees of understanding science, each of which is progressively more complex: The phenomena (macroscopic), the particle (microscopic), and the symbolic (Johnstone, 1991). The most challenging level for students to learn is the micro level, which comprises invisible relations between events, occurrences, circumstances, or concepts (Jaber & BouJaoude, 2012). Visible and sensible phenomena and circumstances are referred to as the macro level. The symbolic level indicates that concepts or concept relations are represented by symbols and formulae (Talanquer, 2011). Literature has shown that students’ misunderstandings and misconceptions about these three levels are caused by their inability to associate them correctly (Adadan, 2013). These investigations have shown that conceptual understandings rise by efficiently connecting micro, macro, and symbolic levels. For instance, most two-year-old children can identify and name the colorless, odorless liquid in a glass as being water because they are familiar with the properties of the phenomena of water. A second way to represent water is that the atomic particles hydrogen and oxygen make up the molecules that makeup water, which is a collection of particles with attraction forces between them. Representing water based on its physical properties is simpler than atomic particle representation. Using the symbols for hydrogen and oxygen to symbolize the formula is a third approach to representing water H₂0. The students who have a solid conceptual understanding of water incorporate these three methods of water representation in long-memory (Gabel, 2015).

Understanding how students learn and how long-term learning happens has been a recurrent problem in science education for over a century. The teaching and learning of sciences have various methodologies which provide the chance for students and teachers to teach and learn process leading to the development of positive attitudes toward science and making the learning of science easier and more meaningful (Stull et al., 2017). Unfortunately, most students leave class with little or no knowledge about the topic learned because they are frequently overloaded with facts during teaching-learning (Duit & Treagust, 2003). The students must memorize scientific concepts and develop the ability to think out of the box and solve problems independently (Freeman et al., 2014). Many studies argued that teaching methods and textbooks are the sources of students’ misconceptions (Barke et al., 2009). The most recent chemistry textbooks are full of inspiring displays and graphics of valuable data. However, texts still fail to create strong connections between chemical topics and real-world applications for students. Deficiency interaction is a severe challenge in science education textbooks alone do not assist in posing questions or developing conceptual understanding (Meyer et al., 2003).

Laboratories play an important part in science education, and science cannot be taught effectively to students without practical experiences in school laboratories (Hofstein & Lunetta, 2004). Student hands-on experiment (SHE) is a common teaching method used in secondary school laboratories. SHE is a method whereby chemistry students are actively engaged in learning activities by handling chemicals and apparatus by themselves by following protocol prepared by the teacher. Hofstein, (2004) suggested that SHE is materials-centered activity, manipulative activities which students make use of during class instruction that help them develop techniques for observing and testing everything around the learning tasks. SHE has become popular, especially in science, technology, engineering, and mathematics. Like other commonly-used concepts, SHE has many meanings and explanations. SHE is referred to as a learning approach in which students are assigned a task to carry out via handling apparatus and chemicals which help them to develop scientific skills such as investigation and problem-solving, enabling them to quickly understand scientific theories and principles (Hensiek et al., 2016; Ramadhani & Titisari, 2019; Towns et al., 2015). SHE helps students by engaging them in in-depth investigations with materials, objects, and phenomenal/ideals such that they can draw meanings and understanding from those experiences.

SHE can be used to train students’ skills, such as: (1) providing opportunities for students to apply and integrate the knowledge and skills they have in practice; (2) proving something scientifically; and (3) appreciating the knowledge and skills possessed (Indriastuti & Priyantini, 2013; Ratmini, 2017). However, the time and resources available might hinder the use of SHE. To address this challenge teachers may use Teacher based demonstration experiment (TBDE) (McKee et al., 2007). It is defined as a method of teaching that involves presenting something audio-visual, such as an explanation of an idea or product and is also known as a teacher-centered approach because learners participate little and the teacher dominates the entire process (Chen & Liu, 2020).

Nowadays, learning science aims to enable students to understand concepts, develop critical thinking ability and creativity skills, and solve real-life problems independently (Mc Donnell, 2007). Since 2016, Rwanda’s education policy has shifted from a knowledge-based curriculum (KBC) to a competency-based curriculum (CBC). The main objective of this change is to train students according to the learner’s needs, society, and the job market. The CBC is aligned with Rwanda’s educational mission of developing a scientific and progressive society. The CBC will also provide a good solution to the high number of unemployed high school leavers since it aims at training students to be more competent in the labor market. This could be achieved by encouraging students to engage in authentic learning instead of knowledge-based learning. Learning science tends to develop knowledge and skills via scientific inquiry and applying scientific knowledge.

Since CBC was implemented in Rwanda, many researchers have studied different active learning approaches, including task-based learning (Musengimana et al., 2022), collaborative learning (Mutwarasibo, 2013), PhET Simulations and YouTube Videos (Ndihokubwayo et al., 2020; Bwalya et al.,2023), Cooperative learning (Sibomana et al., 2021). However, none of these studies explains the kind or degree of knowledge that is measured; do they assess, for instance, rote memorization, recall, paraphrasing, looking for connections between different pieces of information, or applying the newly learned knowledge to events that occur in daily life? The latter two are thought to comprise meaningful conceptual understanding which is achieved through authentic learning such as engaging students in laboratory activities where students could handle chemicals or manipulate laboratory equipment by themselves. These laboratory activities provide students with the chance to experience the macroscopic nature of reactions. Laboratory experiment also provides students the chance to see phenomena with their own eyes, including the transformation of a solutions’s color or the formation of a new product (Wang et al., 2022). A laboratory experiment is said to aid in developing students’ knowledge of science, scientific research, and how science relates to daily life (Barnett & Hodson, 2001).

Despite the importance of the laboratory in the teaching-learning process, chemists continue to ignore the lack of evidence of this vital form of teaching (Bretz, 2019). Sansom and Walker (2020) calls for researchers to conduct more studies to provide sufficient evidence of laboratory experiments in teaching. Thus this study will assess the effect of laboratory experiments provided in two forms of teaching in the secondary school laboratory: TBDE and SHE on students ‘conceptual understanding of solutions and titration. This unit covers three main subtopics including preparation of the solutions, acid-base titration, and redox titration, and is a basic foundation for high studies. In the Rwandan chemistry curriculum, the unit of solutions and titration is taken in senior five (Grade 11).

1.1. Learning by doing theory

In contrast to learning via watching others perform, reading others’ instructions or descriptions, or listening to others’ instructions or lectures, learning by doing refers to learning from experiences that directly emerge from one’s activities. Watching, reading, and listening are all activities, of course. However, they are not the kinds of actions referred to as ‘learning by doing’ since they produce direct experience with actions that are described or demonstrated rather than actual acts that the learner performs (Reese, 2011). Several theorists published works related to this theory, such as Dewey’s model (Dewey, 1986). Later Kolb published an important book on learning by doing theory; the researcher went through four-stage: 1. Concrete experience. In this step, the author showed that a task must be to a group or individual student. 2 Reflective observations, learners take time to recall and think about what they have done and experienced. 3. Abstract conceptualization In Kolb’s model, passive learning is inefficacy. 4. Active experiential learning (doing). Chemistry is full of abstract concepts that seem difficult for students to understand without practical activity.

The activities in a scientific lab allow students to experiment and construct their understanding (Kapici et al., 2019). To make learning more efficacy, the learner must interact with the environment. In other words, the individual or a group of students must be engaged and fully involved in active learning. In chemistry, students need to use their hands to manipulate chemicals/lab equipment to make their observations, develop practical skills, develop scientific reasoning, understand the nature of science, and develop teamwork skills. For instance, anyone who has studied mathematics will understand how much simpler it is for the student to observe how the instructor solved the mathematical problem and ′ got the answer than it is for the student to arrive at it themselves. The chemistry experiment operates in the same way. It is simple for the student to see how the teacher achieves results. However, the student must use his own hands and carry out the task at hand to examine the details of the experiment (Bowers, 1924). By carrying out titration, learners may observe color change as the experiment goes on, which may enhance thinking to such activities, thus enhancing critical thinking and creativity ability towards such activities.

Generalizations or concepts can be generated from the feelings and thoughts emerging from this reflection. Therefore, generalizing concepts would enable the student to solve problems independently. Some recent studies on learning by doing found effective results. For instance (Ajayi & Ogbeba, 2017) examined the effect of the SHE, TBDE, and group discussion on students’ academic achievement in physical chemistry. Their results revealed that SHE laboratory experiments significantly enhanced students’ conceptual understanding compared to students who were taught the same content using conventional TTM. Indriastuti and Priyantini (2013) suggested that the SHE can be used to teach students the necessary skills, including (1) giving them opportunities to use and integrate their knowledge and skills in practice; (2) proving something scientifically; and (3) appreciating the knowledge and skills already possessed. Another study by Juriševič showed that engaging students in laboratory experiments improve both students’ academic achievement and attitudes. Students’ full engagement in practice is a unique way to develop from beginners and take on more responsibility for scientific research as they advance their education (Bretz, 2019). One of the significant pillars of producing future generations of successful scientists is learning chemistry with an effective teaching method. However, Khalili (2001) suggested that educators can change teaching approaches and curricula in favor of SHE.

2. Research methodology

2.1. Research design and sampling

The study employed a quasi-experimental research design, with pre-test post-test non-equivalent and non-randomized control group design (Fraenkel et al., 2012). The participants in this study were 314 senior five (Grade 11) students aged 15–18 years old having chemistry as the main subject in their combinations. Ten schools were selected from four provinces plus Kigali city in Rwanda. The schools were selected purposively based on whether a school had a chemistry laboratory. After sampling, all participants were administered a pre-test to measure students’ prior knowledge about solutions and titration. The students were divided into three groups one group was taught using the SHE, another was taught to TBDE, while the third group was taught using the TTM. The intervention took four weeks based on seven periods per week. One week after intervention, a post-test was administered to all groups to evaluate the effect of the three teaching methods on students’ conceptual change about solutions and titration.

The unit of solutions and titration was taught using three different teaching methods described below.

2.1.1. TTM

The TTM was employed for the control group, where the concepts of solutions and titration were taught using TTM, textbooks for worked examples, and a chalkboard. The majority of the whole class conversation was dominated by the teacher’s explanation and asking a question to an individual or the entire class. The teacher employed the usual method, and students spent most of their time listening to the teacher and taking notes. To demonstrate the titration process, the teacher had to draw a titration setup on the chalkboard. The teacher also asked the students to draw and interpret the titration setup by themselves. Students were given textbook homework relating to preparation solutions and titration. The students in this group completed the solutions and titration classes without laboratory experiments.

2.1.2. TBDE

Students in this group were first taught the concepts of solutions and titration using TTM. Students also had laboratory experiment sessions. One day before the laboratory activity, the students were given experiment procedures and instructions written on a sheet of paper to allow them to be familiar with the experiment to be done. Before the demonstration, the teacher had to carry out all experiments in the preparatory room to ensure that experiments could be successful because unsuccessful experiments may create distrust in students. During laboratory activities chemicals and apparatus were put on the table and students were asked to sit around the table so that they can observe easily. All experiments were carried out by the teacher while students were observing, taking notes, or asking questions to the teacher. Students were encouraged to carefully observe the reaction process and predict the outcome of the experiment on color change or to write the chemical equation of the reaction taking place, but they were never allowed to conduct their experiment.

2.1.3. SHE

In this group, students had normal classes to learn the theory of solutions and titration, after that students had some laboratory sessions. The laboratory work was designed based on the learner-centered method. During laboratory activities, the students spent the majority of their time conducting experiments in groups of 3–4 students. The students were given experiment procedures and instructions written on a sheet of paper one day before the laboratory activity to familiarize them with the experiment to be done. The teacher facilitated students’ discovery of knowledge rather than delivering knowledge. Students actively participated in the learning process to get the opportunity to build technical and manipulative skills. For example, during the exercise related to solutions preparation, the teacher requested students to describe the meaning of 5% and 5.5% alcohol found on the bottles of PRIMUS and MUTZIG, respectively. These are Rwandan beers brewed locally. Aside from the questions, the teacher asked the students to notice every change that occurred during laboratory practice, make a prediction of the experiment outcome, and write down the chemical reaction. For instance, during iodometry titration, students were required to name the color change, guess the product formed, and write down the chemical reaction when a potassium iodate (V) solution was mixed with an excess potassium iodide solution. In summary, SHE students become actively involved in laboratory activities by handling chemicals and laboratory equipment on their own. The teacher’s function was also that of a facilitator.

2.2. Data collection tool development and its validation

Quantitative data in this study were collected through a chemistry achievement test (CAT). The CAT was composed of 30 multiple-choice questions that measure students’ achievement of solutions and titration for S5 students taking chemistry as one of the major subjects in their Rwandan curriculum combination. Initially, 53 potential items were selected from different chemistry textbooks, syllabuses, and national exam papers. In validating this achievement test, we invited six evaluators (three chemistry teachers from secondary and three lecturers from college in chemistry education). In order to assign each of the 53 prepared questions to Bloom levels we explained the levels of Bloom taxonomy to them and asked them as follow:

Remember (knowledge): Can the learners remember key factors and terminology? (Recall facts and basic concepts)

Understand (comprehension): Students then move up to understanding, using the knowledge they gained in the previous level. (Explain ideas or concepts).

Apply: At this stage, learners are expected to apply their knowledge and understanding in a particular way. (Use information/knowledge in new situation)

Analyze: This is a high-level skill that requires more cognitive processing than lower-order skills. (Draw connection among ideas)

Evaluate: Evaluating material is only possible once the lower-order skills have been mastered. (Justify a stand or decision)

Create: Creating new or original work is the highest level of thinking and requires the deepest learning and greatest degree of cognitive processing. (Produce new or original work). We got all their feedback. We analyzed them by taking the most compromised level. For instance, on question_1, two evaluators have assigned it to remembering (first level), two evaluators assigned it under the understanding level, and one evaluator assigned it to applying phase. Thus, we assigned it to the second level (understanding) as it is between of assigned levels (first and third). However, on question_2, since one evaluator assigned it to application, another one assigned it to analyzing level, while the other three assigned it to understanding, we then decided to assign it where many evaluators have assigned it (Understanding).

After assigning all the items, 16 questions covered remembering, 14 covered understanding, 17 covered applying, 5 covered analyzing, 0 covered creating, and one covered evaluating level. Then we selected 5 questions for remembering, 10 questions for understanding, 10 questions for applying, and 5 questions for analysis. Thus, a total of 30 questions comprised the final test. Before implementation, this 30 items test was pilot-tested with sixty S5 chemistry students to assess its validity and reliability, and a medium Pearson product-moment correlation coefficient over time of r = 0.54 was achieved. Data collection started in April 2022 and lasted for four weeks based on seven hours per week.

2.3. Data analysis

Before data analysis, the filtering process was done to remove students who missed either the pre-test or post-test. The correction was done in MS Excel using the IF EXACT function, one point was given for each correct answer, and thus maximum score was 30. After marking each question, we calculate the sum and percentage score for each question. For instance, in the group TTM pre-test, 51 students responded with the correct answer to the first question out of 104 students who sat for the test; therefore, the percentage score of the first question was 49. The same process was applied for all questions, in all groups as well as for both pre-test and post-test. We further calculated the average of all questions that compose each bloom’s taxonomy level. For example, for the TTM group, the remembering level students’ score percentages are 49,48,39, 28, and 8; therefore average score in the remembering level in the TTM group for the pre-test is 34. The same was done for all levels, in all groups, for both pre-test and post-test. To understand the effect of three teaching methods on Bloom’s taxonomy level, we compared the average percentage scores by taking post-test average percentage scores minus the pre-test average. For example, the TTM group scored an average percentage in remembering the level of 34 and 43 for the pre-test and post-test, respectively, leading to an increase of 9% in conceptual understanding in terms of remembering questions.

3. Research results

3.1. Assessing students ‘prior knowledge about concepts of solutions and titration before intervention

The current study intends to measure the effectiveness of three teaching methods: TTM, TBDE, and SHE, on students ‘conceptual change of solutions and titration. A preliminary analysis was conducted to assess students ‘conceptual understanding of solutions and titration before intervention—Figure 1. Illustrates pre-test results for all three groups on conceptual understanding of solutions and titration concepts before intervention. The results show that students in the TTM and SHE groups were on the same level with the same mean score of 41% while the mean score of TBDE group was 3% higher than both TTM and TBDE groups. Students performed differently on different questions. Questions 7, 8, 9, 12, and 17 were found to be easiest for all groups. For example, about 88%, 94%, and 92% of students for TTM, TBDE, and SHE respectively answered the correct answer on item 7. On the other hand, 5, 15, 18, 26, and 29 seemed difficult for all groups. For instance, only 8%, 8%, and 9% of students for TTM, TBDE, and SHE respectively were able to select the right answer on item 5.

Figure 1. Pre-test percentage score of each item. Note: the horizontal axis displays 30 items of CAT while the vertical axis represents the percentage of students who answered the correct answer on each item.

3.2. To what extent do TTM, TBDE and SHE impact students ‘conceptual understanding of solutions and titration?

To understand the effect of the three teaching methods on students ‘conceptual understanding of solutions and titration, we examined each question’s pre-test and post-test percentage scores. Figure 2 provides information on the change in percentage scores of students who answered correctly for each question after the intervention. Overall, both SHE and TBDE positively impacted students’ percentage average scores on most items. However, the TTM method could only improve students ‘conceptual understanding of knowledge-based questions (lower level) while showing slight improvement or causing misconceptions for other levels. Students TTM were confused about many questions beyond the remembering level. For the second level (understanding), they showed remarkable misconceptions on questions 7, 8, 9, 10, and 13. That means students taught by TTM were confused on 5 out of 10 questions in understanding level. The TTM showed slight improvement or misconceptions for the remaining levels (applying and analysis).

Figure 2. Post-test percentage score of each item. Note: the horizontal axis displays 30 items of CAT while the vertical axis represents the percentage of students who answered the correct answer on each item.

On the other hand, the addition of laboratory experiments enhanced students’ conceptual understanding in the SHE and TBDE groups. Students in SHE and TBDE groups improved conceptual understanding throughout all four levels of Bloom’s taxonomy. Both SHE and TBDE also improved students’ percentage scores for difficult questions before intervention. For instance, question 5 was difficult for all students before intervention. However, students in TBDE and SHE groups increased to 24% and 12% percentage scores, respectively, while students in the TTM group improved by just 1%. Likewise, questions 15 and 18 were difficult before intervention. They looked more feasible for students in SHE and TBDE after the intervention. This suggests that a laboratory experiment is remedial that could tackle the abstractness of chemistry and enhance students ‘conceptual understanding. However, SHE appears more effective as we move to the high level of bloom’s taxonomy. Students in SHE groups outperformed TBDE and TTM students for 3 out of 5 questions in the level of analysis. Although both SHE and TBDE improved students’ conceptual understanding better than TTM a negative trend in percentage scores at some items was observed in all groups. For example, in TTM groups, students answered correctly on items 7 and 13; the percentage score decreased from 79% and 53% to 71% and 46%, respectively. In the TBDE group, the percentage score on items 2 and 10 decreased from 63% and 42% to 55% and 33%, respectively. In comparison, in the SHE group, the percentage score on questions 7 and 12 fell from 92% and 85% to 89% and 54%, respectively.

3.3. How do TTM, TBDE, and SHE affect students’ scores on Bloom’s taxonomy levels?

To understand the effect of the three teaching methods, TTM, TBDE, and SHE, on knowledge domains, we examined the average percentage scores of the first four Bloom’s taxonomy levels, namely remembering, understanding, applying, and analysis Figure 3. Both SHE and TBDE groups showed the upward trends throughout all Bloom’s taxonomy levels. In contrast, students in the TTM group only showed improvement in the remembering level and a slight increase in applying and analysis levels. In contrast, they showed a negative trend in the level of understanding. The TTM increased students’ conceptual understanding by 9%, 9%, and 6% average percentages in remembering, applying, and analysis, respectively. At the same time, a negative trend was observed in the understanding domain.

Figure 3. Students’ conceptual understanding of solutions and titration to Bloom’s taxonomy. Note: the horizontal axis displays the first four knowledge domains of Bloom’s taxonomy while the vertical axis represents the average increase or decrease (%) in conceptual understanding of each knowledge domain.

Surprisingly TBDE showed the highest average percentage score at the applying level, increasing by 4% compared to the SHE group. On the other hand, both SHE and TBDE enhanced students ‘conceptual understanding throughout all levels. SHE outperforms TBDE by 9%, 2%, and 4% in the levels of remembering, understanding, and analysis respectively. These results indicate that students should be allowed to manipulate and handle chemicals and laboratory equipment by themselves. Although both SHE and TBDE improved students’ conceptual understanding better than TTM in the first three levels, remembering, understanding, and applying, a decrease in improvement was observed for all groups at the level of analysis. For example, SHE and TBDE increased by just 8% and 5% respectively in the level of analysis. This improvement seems to be small compared to what we observed in the first three levels. This finding suggests that these types of laboratory exercises where students work on laboratory experiments by following a prescribed experimental protocol do not allow students to develop high-order thinking skills.

4. Discussion

This study aimed to investigate the effect of three teaching methods, namely TTM, TBDE, and SHE, on students ‘conceptual understanding of solutions and titration. This study emphasized improving senior five or grade 11 students’ conceptual understanding of solutions and titration through SHE and TBDE. After the intervention, all three groups increased their overall average percentage in conceptual understanding; however, the TTM group could not gain as much as in SHE and TBDE groups. Both SHE and TBDE groups scored higher for most questions than students in TTM. The results indicate that the laboratory experiment enhanced students’ conceptual understanding of solutions and titration compared to students in the TTM group who studied the same unit by traditionally following the teacher. This finding is attributed to the effect of laboratory experiments providing an opportunity for students to experience the macroscopic nature of reactions such as color change with their naked eyes (Kennepohl, 2021).

Although both SHE and TBDE groups improved students conceptual understanding of solutions and titration better compared to the students in the TTM group, SHE group surpassed the TBDE group by around 2% in overall average percentage in conceptual understanding. From these findings, we argue that students’ direct contact with chemicals or laboratory materials enhanced students ‘conceptual understanding. The current results are consistent with previous studies Özmen et al. (2009) argued that laboratory exercise significantly improved students ‘conceptual understanding of acid-base titration compared to their counterparts who studied the same concepts by the conventional method. The researcher further suggested that engaging students in laboratory experiments helped them to overcome alternative conceptions and promoted an understanding of acid-base chemistry at the molecular level.

Another remarkable point was on items 5, 15, and 18, where students showed notable misconceptions before intervention. Laboratory experiments promoted deep understanding leading to an increase in percentage scores on the items mentioned above compared to the students in the TTM group. Despite the influence of laboratory experiments in SHE or TBDE groups, misconceptions were observed in all groups at some items. For instance, students in the SHE group showed a decrease in percentage scores on items 12, 21, 23, and 30. At the same time, a negative trend was also observed for students in the TBDE group on items 2,10,28, and 30. This is not a surprise because no teaching method could eliminate misconceptions a hundred percent. Whenever students get into a more challenging subject, a different type of problem develops: That is a school-made misconception (Barke et al., 2009).

To understand how these teaching methods affect different levels of Bloom’s taxonomy, remembering, understanding, applying, and analysis, we analyzed the average percentage score of each level. The results show that the TTM method has little effect in improving students ‘conceptual understanding and seems to decrease as we move to the high level of learning domains. This finding suggests that students taught by the TTM are always given the definition of the concepts to memorize without comprehending further connections to concepts besides those mentioned in the definition (Lu et al., 2018).

In comparison to SHE and TBDE groups TTM had a slight improvement in the levels of applying. At the same time, a remarkable misconception was observed in the understanding level. This negative trend was probably caused by chemistry calculations or textbooks used in the TTM group (Supatmi et al., 2019). However, the results indicate that both SHE and TBDE groups scored higher in all three first levels, remembering, understanding, and applying. From the current results, it is clear that laboratory activities provided through TBDE or SHE is a vital tools that could help students acquire lower- and high-level learning domains. We argue that engaging students in laboratory activities by handling chemicals and laboratory equipment promotes understanding and thinking skills (Özmen et al., 2009). Laboratory activities through SHE experiments provide students with experience and present a particularly attractive opportunity for inquiry-driven and open-ended inquiries that develop independent thinking, critical thinking, reasoning, and a perspective of chemistry as a scientific process of discovery (Bretz, 2019).

It is believed that SHE allows students to develop skills and apply the knowledge they gained in practice (Ramadhani & Titisari, 2019). Students in the SHE group were expected to get high scores in the application domain; surprisingly, students in the TBDE outperformed both SHE and TTM groups at the application level. This finding confirms the contradictory recent published results between laboratory exercises provided through TBDE and SHE. For instance, Logar & Savec (2011) compared the effectiveness of three teaching pedagogies SHE, TBDE, and TTM. They found that students who were taught by TBDE outperformed those who were taught by SHE activities. McKee et al. (2007) investigated the effects of TBDE and SHE. They concluded that there was no difference between the two groups regarding students’ conceptual grasp of chemistry.

On the other hand, Ajayi and Ogbeba (2017) reported that SHE enhanced students’ conceptual understanding of stoichiometry better than TBDE. Another study by Stull et al. (2017) examined students who learned chemistry using 3D molecular models. Their results revealed that Students who viewed teacher demonstrations and then independently played the video outscored those who only watched teacher demonstrations. A considerable debate on this point needs to be clarified in further studies.

Despite the positive impact of laboratory experiments in the first three knowledge domains, remembering, understanding, and applying, a decrease in conceptual understanding was observed for all groups at the level of analysis. This finding is because these types of laboratory experiences where students follow a protocol prepared by the teacher do not allow students to develop critical thinking skills. The level of studying is too limited and students are unaware of the goals of a practical and how the outcomes relate to the theory presented in the lecture program. Furthermore, these types of laboratory exercises frequently offer the little possibility for innovation or contextualization and are either a verification of a known amount or a testing of a theory provided in lectures (McGarvey, 2003; US NRC, 2005). Therefore we strongly recommend further studies to explore the effect of inquiry or problem-based learning laboratories on high school students’ conceptual understanding of solutions and titration across different knowledge domains. Outcomes from such studies will help our understanding of how to best shape citizens equipped with 21^st-century knowledge and skills.

The current study suggests that laboratory experiments may improve students’conceptuatual understanding of solutions and titration because students were engaged in observation, investigation, facts, analysis, and interpretation of the results based on the SHE, which is the context of the real world. It is effective for students to participate in the learning process to build scientific knowledge and produce meaningful learning for them (Cetin-Dindar & Geban, 2017).

5. Conclusion

This study examined the effect of three teaching approaches: TTM, TBDE, and SHE on the conceptual understanding of solutions and titration of secondary school students. The significant finding is that combining TTM with laboratory experiments provided through TBDE or SHE enhanced students’ conceptual understanding of solutions and titration compared to students who taught the same unit using TTM alone. The results indicate that TTM alone is adequate for the lower level of Bloom’s taxonomy (remembering) and shows a slight improvement in student conceptual understanding or causes misunderstanding as we move to the high level of Bloom’s taxonomy. On the other hand, the combination of TTM with laboratory experiments could enhance students ‘conceptual understanding of remembering, understanding, and applying levels. Although supplementing laboratory experiments through SHE or TBDE improved students’ conceptual understanding in the first three levels of knowledge domains better than TTM alone, the effectiveness of both SHE and TBDE appears to be decreased in the level of analysis. This finding is because these types of laboratory exercises where students follow an experiment protocol prepared by the teacher do not allow students to develop critical thinking skills.

5.1. Recommendations

Based on the findings chemistry teachers are encouraged to use laboratory experiments in teaching solutions and titration to enhance students’ conceptual understanding and help them to develop critical thinking skills. Additionally, we recommend further studies to examine the effect of inquiry-based learning laboratories on secondary school students’ conceptual understanding of solutions and titration. We also recommend extending the study to other schools within Rwanda to cover a large sample as this study was restricted to 10 schools found in 4 provinces only.

Disclosure statement

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

Data availability statement

The data used for this study can be made available upon request from the corresponding author.

Additional information

Notes on contributors

Pascal Kaneza

Pascal Kaneza is a PhD student in chemistry education at the University of Rwanda. His research interests in assessing the effect of hands-on vs demonstration experiments students’ performances and competences in chemistry. ORCID: 0000-0002-9275-2183

Jean Baptiste Nkurunziza

Jean Baptiste Nkurunziza holds a PhD in Chemistry from Mangalore University, India. He also has a Postgraduate Certificate in Learning and Teaching in Higher Education (PGC LTHE) from Kigali Institute of Education. He is currently working as a Senior Lecturer of Chemistry at the University of Rwanda - College of Education. Jean Baptiste is the Principal Investigator of the project entitled “Production of Low-cost chemicals for effective teaching and learning of Chemistry at Lower Secondary Schools in Rwanda”. His current research projects focus on the synthesis of bioactive compounds and Science Education. His publications can be found at 0000-0001-9386-7161

Innocent Twagilimana

Innocent Twagilimana is holder of a PhD in Education from the Witwatersrand University (South Africa), a professional Degree in Monitoring & Evaluation of Educational projects from Cheick Anta Diop University (Senegal), and conducted his postdoctoral studies at the Stockholm University (Sweden) in integration of technologies in education. He also studied and received academic qualifications from the National University of Rwanda, Mons-Hainaut University (Belgium), and the University of the Western Cape (South Africa). Previous responsibilities at both academic and administrative levels: journalist at Rwanda Television before joining the former National University of Rwanda as lecturer and Deputy Director of the Academic Quality Unit; Head of Department (Educational Foundations, Management and Curriculum Studies); was often involved in research projects as Principal Investigator. Worked as consultant with a number of Civil Society Organisations since 2003. Currently Senior Lecturer and Dean of School of Education, University of Rwanda. ORCID ID: 0000-0003-1579-5099

Thumah Mapulanga

Thumah Mapulanga is an experienced biology teacher at the secondary school level in Zambia. Currently, he is a PhD student in biology education at the University of Rwanda. He is also a part-time lecturer of biological sciences at the University of Rwanda, College of Education. His research interests are in biology teachers’ pedagogical content knowledge (PCK) and science teaching-learning environments. Lately, his interests have extended to technological pedagogical content knowledge of pre-service and in-service biology teachers (TPACK). ORCID: 0000-0002-5609-3539

Anthony Bwalya

Anthony Bwalya is a lecturer of biological sciences at Kwame Nkrumah University in Zambia. He is a PhD student in biology education at the University of Rwanda. His research interests are in pre-service teachers’ technological pedagogical content knowledge (TPACK). ORCID: 0000-0003-3056-2955