Active versus passive learning: Comparative case study of problem-solving competencies in stoichiometry

Teaching methods can help learners to develop problem-solving skills and enhance their achievement in stoichiometry. Process oriented guided inquiry learning (POGIL) is one of the teaching methods that promote problem-solving skills because it provides opportunities for learners to work with many formulae through many steps in solving problems such as stoichiometric calculations of number of moles and concentration of solutions. To understand how POGIL can improve learners ’ achievement and develop problem-solving skills, four grade 11 physical sciences classes of mixed gender and multicultural black learners were purposefully and conventional sampled from four different township schools in Pretoria, South Africa. Through pre-and post-test case study and lesson observations, two different independent groups (POGIL group and lecture group) were included in the study. POGIL group constituted 48 students, while lecture group 62 students taught by their respective teachers at their schools for three weeks using English second language. The results from the pre-test suggest that learners in all the four classes lacked problem-solving competencies in solving both the low-order and the high-order stoichiometry questions. According to the research interpretation, lesson observations of POGIL were active learning while lecture method was passive learning. The post-test results indicate statistically significant greater problem-solving competencies in POGIL group than in the lecture group. The study recommends the use of POGIL in teaching stoichiometry.


INTRODUCTION
South African (SA) learners demonstrated challenges in stoichiometry on topics such as the mole concept, the quantities of products and reactants, and the limiting reactants (Department of Basic Education [DoBE], 2019).Competence in stoichiometry calculations challenges both teachers and learners (Stott, 2021).SA teachers without bachelors' degree focus on algorithm calculations and less on conceptual understanding (Stott, 2020).SA learners have misconceptions and fear in answering stoichiometry questions (Booi, 2023;Miheso & Mavhunga, 2020).
This study is part of a PhD thesis completed in 2021.
SA university students fail to balance equations of reactions and identify the limiting reactant and the reaction yield (Marais & Combrinck, 2009).For this reason, teacher education in SA ought to focus on competencies in solving calculations and proportions (Stott, 2021).Therefore, the development of in-service teacher programs to enhance the teaching of stoichiometry is recommended to mitigate the deficiencies in teaching stoichiometry and chemistry (Malcolm et al., 2019;Stott, 2021).Use of inquiry methods such as process oriented guided inquiry learning (POGIL) reduce misconceptions in stoichiometry (Mamombe et al., 2021).One of the approaches is to use sub-micro diagram, which is 2 / 15 believed can improve university students' understanding of stoichiometry (Davidowitz et al., 2010).
Elsewhere, similar challenges in stoichiometry have been observed.Zimbabwean high school learners presented similar challenges in solving stoichiometry (Mandina & Ochonogor, 2018).Use of simulations increased conceptual understanding of stoichiometry in Lesotho (Mohafa et al., 2022).Nigerian learners taught using problem-solving techniques performed statistically significantly better than those taught using the lecture method (Sunday et al., 2019).It appears that the use of active teaching methods may alleviate the challenges of conceptual understanding, problemsolving skills, and misconceptions.
The current approach is POGIL, which is a learnercentered problem-solving strategy, where learners collaboratively solve worksheets in small teams of three, four, or five (Simonson, 2019).The learners work from the familiar, too simple, and then complex constructs helping them solve abstract problems under the guidance of teachers who are acting as facilitators (Moog & Spencer, 2008).POGIL worksheets are developed to follow a learning cycle (Lawson, 1988).The current study compared POGIL and lecture methods on learners' problem-solving competencies in stoichiometry.In the context of this study problemsolving competency is the learner's ability to successfully solve both simple and complex stoichiometry problems (Bodner & Herron, 2002).POGIL has been observed to increase SA high school learners' understanding and achievement of stoichiometry (Mamombe et al., 2021).Students who were taught design patterns using POGIL improved critical thinking, problem-solving, and communication skills (Lotlikar & Wagh, 2016), making POGIL a statistically significantly more effective approach in teaching practical chemistry than the lecture method (Omoniyi & Torru, 2019).
The current study was a pre-and post-test comparative study of the effectiveness of POGIL and lecture method on grade 11 learners' problem-solving competencies in stoichiometry.
The main research question was, as follows: 1. What is the effect of teaching approach on learners' problem-solving competencies in stoichiometry?
The sub research questions were, as follows: a. What is the relationship between learners' problem-solving competencies in stoichiometry in POGIL group compared to the lecture group before the intervention?b.What is the relationship between learners' problem-solving competencies in stoichiometry in POGIL group compared to the lecture group after the intervention?c.How did the classroom activities of both teachers and learners in POGIL classes compare to the lecture classes?
The current study focused on comparing, quantitatively, the problem-solving competencies of learners in POGIL group to those in the lecture group after instruction.The study further analyzed the difference in problem-solving competencies by evaluating the learners' activities during the lessons.The current study was guided by interactive-constructiveactive-passive (ICAP) framework, which assessed the learners' engagement during lessons.

LITERATURE REVIEW
Challenges experienced by SA high school learners in the chemistry section of physical sciences have been observed and documented (DoBE, 2020).SA high school learners have demonstrated misconceptions about the dissolution of salts (Kibirige et al., 2014), force (Kibirige & Mamashela, 2022), and stoichiometry (Stott, 2021).University students in SA have demonstrated limitations in stoichiometry, particularly the symbols Contribution to the literature • The study is set in a specific cultural and educational context, offering insights into the challenges and successes of implementing active learning strategies in South African township schools.This adds to the literature on educational reforms and teaching methodologies in diverse international contexts.• By employing both quantitative and qualitative methods, the study provides a comprehensive analysis of the impact of teaching methods on student learning outcomes.This mixed-methods approach enriches the literature by showing not only the effectiveness of POGIL but also the classroom dynamics and student engagement patterns that contribute to learning outcomes.• This study provides a detailed case study of how innovative teaching methodologies can improve learning outcomes in specific scientific disciplines and educational settings, thereby supporting calls for broader educational reforms that embrace active learning.
The challenges of learners in stoichiometry seem to be universal, hence the need for addressing these by using alternative teaching methods.
Use of POGIL improved learning outcomes in American learners (Hu et al., 2016) and equally improved SA learners' understanding of stoichiometry (Mamombe et al., 2021).Learners' achievement in stoichiometry is directly related to their mathematical problem-solving skills and conceptual understanding (Owoyemi & Amahwe, 2020).The use of problemsolving instruction was effective in remedying learners' difficulties in stoichiometry (Mandina & Ochonogor, 2018).
Lesotho science teachers demonstrated lack of effective pedagogical skills in stoichiometry (Makhechane & Qhobela, 2019).Stoichiometry has challenged learners of different nationalities and teachers alike, even though teacher development programs have been crafted to assist teachers in the teaching of stoichiometry (Malcom et al., 2019).
POGIL method promotes active engagement of learners (Strachan & Liyanage, 2015).Use of active engagement may result in improved conceptual understanding (Simonson, 2019).POGIL, therefore, may impact cognitive development of learners as they invent concepts and develop understanding (Moog & Spencer, 2008).
The collaborative teams in POGIL classes may provide platform for teamwork, whereby learners assist each other (Simonson & Shadle, 2013).For this reason, the learners taught using POGIL may improve problemsolving skills and other process skills like communication, and critical thinking, among others (Moog & Spencer, 2008;Simonson & Shadle, 2013).While some teaching methods may partially develop learners to solve simple calculations, POGIL may lead to learners solving both simple and complex questions (Simonson, 2019).This has a direct impact on improving motivation and achievement of the learners (Santoso et al., 2023).

CONCEPTUAL FRAMEWORK
An ICAP framework guided this study (Chi et al., 2018).ICAP framework is a constructivist theory, which defines cognitive engagement activities based on students' overt behaviors.It proposes that engagement behaviors can be classified into four modes of engagement, which are interactive, constructive, active, and passive engagements.During 'constructive engagement' learners individually construct knowledge by writing own notes, drawing a concept map, predicting, inventing, or self-evaluating one's own ideas (Simonson, 2019).
The 'interactive engagement' is when two or more learners collaboratively elaborate, justify, explain, question each other's ideas, and add-on to each other's idea until they reach consensus.Both the 'interactive' and 'constructive modes' of engagement involve information processing and problem solving.'Active engagement' is associated with manipulative skills such as pointing to, or gesturing, repeating, copying, rehearsing, underlining, or choosing.'Passive engagement' is when learners are listening to instructions, reading a text silently, or watching a video, without undertaking any visible activities.The 'passive mode' of engagement involves low order thinking skills.When learners are doing what they are expected to do in the interactive, constructive, active, or passive modes, they are in the 'engaged mode'.If they do other activities apart from the assigned task they are in the 'disengaged mode' (Chi et al., 2018).
ICAP framework defines the combination of the interactive, constructive, and active modes as "active learning modes".Active learning is associated with learner-centered teaching methods such as POGIL, where learners are engaged in activities that are guided by a learning cycle (Lawson, 1988).
Passive learning is associated with teacher-centered methods like lectures.However, during active learning methods, there are moments when learners are passive and sometimes disengaged.On the other hand, in passive learning methods, there are moments when learners may be engaged in the active mode of learning.Therefore, modes of cognitive engagement during active and passive learning methods may overlap.Figure 1 shows a simplified drawing of ICAP framework.Thus, ICAP framework, as applied in this study, was used to differentiate learners' modes of cognitive engagement during both POGIL and the lecture lessons.This seemed ideal in monitoring cognitive engagements through the activities of the learners in both the lecture and POGIL classes.Since POGIL is associated with group activities, we assumed the learners' cognitive engagement would be in the "active learning modes".(Chi et al., 2018) 4 / 15 The lecture method is associated with learners listening to the teacher and taking notes thereby classifying the learners' cognitive engagement in the "passive learning mode".The use of pre-and post-test was justified on the basis that all learners answered individually.This defined their 'constructive' mode of engagement.

METHODOLOGY
This mixed method case study compared the effects of a POGIL method and lecture method on learners' problem-solving competencies in stoichiometry tests.A mixed method case study design involves both quantitative and qualitative data collection, analysis, and integration to provide in-depth evidence (Creswell & Clark, 2018).Qualitative data was obtained from observing the learners' engagements during the respective lessons.Quantitative data was obtained from the learners' scores in pre-and post-test.

Sampling
The two teachers who participated in POGIL classes were part of the 25 high school science teachers from a district in Pretoria who participated in a three-day POGIL intervention workshop.This was a professional development workshop facilitated by one university to promote the use of POGIL in schools.These two teachers volunteered to teach stoichiometry to one of their grade 11 physical science classes using POGIL at their respective schools.For POGIL classes, 22 learners at school A and 26 learners at school B consented to participate in the study.The lecture classes comprised 28 learners at school C and 34 learners at school D alongside their respective science teachers.The teachers at schools C and D were unfamiliar with POGIL and used the lecture method in their classes.

Test Instruments
The questions in both pre-and post-test were similar except for differences in the amounts of substances.The questions were set on a continuum of levels of complexity as prescribed in CAPS curriculum by DoBE (2012).The current study was done in SA, where CAPS curriculum serves many of the candidates at both primary and secondary school.CAPS curriculum also prescribes assessment strategies for questions in the formal tests and examinations.

Data Collection
Data were collected using pre-and post-test and lesson observations.The data collection process started with a pre-test, followed by lesson observations, and concluded with the post-test.

Pre-& post-test
Pre-and post-test were similarly designed by adapting the physical sciences examination questions of CAPS curriculum (DoBE, 2012).These tests were initially validated by two senior physical science teachers and two teacher education lecturers.The learners were instructed to answer all questions in full, by showing all the necessary formulae, calculations, and ending with the answer.They were reminded that there were marks allocated for each of these parts of the calculations.The one-hour pre-test was administered by the respective subject teachers during mid-week at their respective schools.
During the third week after the intervention the teachers administered the one-hour post-test to the learners at their respective schools.Both pre-and posttest were composed of ten items of different levels of complexities (see Appendix A and Appendix B).The design on both pre-and post-test were guided by CAPS syllabus, which classifies questions into levels of complexity.
A level I question elicits a definition, a law, or a single-step calculation requiring only one formula.A single step entailed selection of a correct formula, appropriate substitution, and getting the correct answer.A level II question elicits a calculation, which requires a two-step calculation and the use of two formulae.A level three question demands a three-step calculation using three formulae, while a level four question is the most complex question requiring the use of four steps and four formulae (DoBE, 2012).These classifications are related to Bloom's taxonomy of cognitive domains, where a level I question expects recall of basic facts, level II requires understanding, where the learner interprets, and discusses facts.Level III demands analysis and application of knowledge, while level IV expects evaluation and synthesis of ideas (McGuire & McGuire, 2015).Table 1 shows the design of the questions in preand post-test.

Lesson observation
The second stage of data collection after the pre-test was the intervention using POGIL method (experimental group) and the lecture method (control group).The lessons were designed using CAPS syllabus (DoBE, 2012).The intervention lessons were taught by the usual teachers of the sampled classes.Two teachers who were previously trained to teach using POGIL taught one of their classes using the said teaching method.Another two teachers from a different district, who were not trained to teach using POGIL used the lecture method.All the four lessons, which were one hour long were observed by the researcher using the observations schedules (see Table 2) and for learners (see Table 3).
Both POGIL and lecture lessons were conducted at respective schools during weekends to avoid disrupting the normal programs of the schools.Teachers in the lecture classes were allowed to prepare their own lessons plans so that they could teach as they usually did guided by CAPS document.Teachers in POGIL classes used preexisting POGIL worksheets (from www.pogil.org).POGIL worksheets were adapted to SA context by using familiar examples and adhering to the aims and objectives of CAPS syllabus.The learners in both POGIL and lecture classes were taught for a total of four hours divided into two lessons each weekend.During each weekend there were short breaks between the lessons for both POGIL and lecture groups.
To assess the approach used by the teachers, the researcher observed all lessons using observation schedules for teachers (see Table 2) and learners (see Table 3).The observation schedule for teachers was designed to establish the teaching approach in adherence to the roles of the teacher with reference to ICAP framework (Chi et al., 2018).
The observation schedule for the teachers on Table 2 was used by making a tally after the occurrence of the teacher's activities in a period of two minutes.The tallies were recorded every two minutes for the four-hour duration of the lessons.These were recorded during both POGIL lessons and the lecture lessons and were used to define the teaching approach used.The observation schedule for the learners focused on learners' activities to establish their cognitive engagement in relation to ICAP framework (Chi et al., 2018).It was important to focus on learners' engagement to ascertain their cognitive development arising from the teaching approach used.Table 3 shows the observation schedule used for the observation of learners during the lessons.When an action was observed over two consecutive minutes a tally was allocated.In POGIL classes the learners were in teams of four.The observer recorded the group activity since learners in each group coordinated their actions.Learners' actions in the lecture classes were coordinated by the teacher.For that reason, most of the records during the lecture lessons represented the actions of the class.

Data Analysis
Data analysis entailed the interpretation of the data collected using the tests and the lesson observations.

During intervention
The teachers' activities as indicated on Table 3 assisted in the classification of the lesson as POGIL or lecture.The teachers' and the learners' activities were guided by ICAP framework and assisted in data analysis to answer the third sub-research question.The assessment of the actions of the learners translated into the level of cognitive engagement of the learners during the lessons and was facilitated by scaling the learners' activities.The learners' activities were classified according to 'interactive', 'constructive', 'active', 'passive', or 'disengaged' (see Table 4).When the learners discussed the same topic the mode of engagement was recorded as 'interactive' mode.When learners individually brainstormed by putting together their ideas before discussing with their peers the mode of engagement was recorded as 'constructive'.The 'active' mode of engagement entailed manipulative activities such as copying, drawing, underlining, or choosing.The learners' engagement was 'passive' mode when they listened to instructions, read a text, without undertaking any visible activities.The learners' mode of engagement was 'disengaged' when the learners did other activities, which had nothing to do with the assignment.

During tests
Both pre-and post-test were assessed by analyzing the correctness and the number of completed steps in the response.The complexity of the question (see Table 1) determined the classification of the learners' answers (see Table 4).A response was classified as 'novice' if in any type of question there was no response (blank) or there was no single step calculation completed.
An answer was classified as 'elementary' if there was a correct definition or only one step calculation to any type of question.An 'intermediate' answer entailed a response, where two steps were fully completed on a levels II, III, or IV question because it was impossible to have two-steps on a level I question.An answer was classified as 'competent' when three steps were correctly executed in response to a level III or level IV question.It was impossible to have three steps on either level I or level II questions.An answer was classified as 'advanced' when four steps were correctly followed in response to a level IV question.It was impossible to get four steps on level I, II, or III questions.The learners' problem-solving competencies were entailed by the level of the classification of their answer.The learners' scripts were coded initially by the primary researcher and then by the second author.The two coders discussed and reached consensus on the coding.
Table 4 summarizes the classification of responses relative to the question level.
For the purposes of recording the test scores, a 'novice' response was allocated zero points because there was nothing achieved by the learner, an 'elementary' response was allocated one point because the learner completed one step, and an 'intermediate' response was allocated two points because the learner completed two steps.A 'competent' and an 'advanced' response were, for the same reason, allocated three and four points, respectively.The higher the sum of the test scores attained by an individual or class, the higher the competency.
Statistical data analysis was done on the quantitative data from pre-and post-test scores.Descriptive statistics were done to describe the data of both pre-and post-test.Similarities, trends, and differences were identified and to further analyze both pre-and post-test quantitative data about the learners' competencies in stoichiometry inferential statistics was used.Two hypotheses were proposed.
Ho There is no relationship between the learners' problem-solving competencies and the teaching approach.problem-solving competencies and the teaching approach.
The null and alternative hypotheses were used to guide the study by comparing the problem-solving competencies of the learners in the two groups before and after the intervention.Analysis of variance (ANOVA) test was found ideal to use to analyze the test scores of the two groups.
ANOVA test was ideal for this study because there was only one independent variable (teaching approach) and only one dependent variable, which was learners' problem-solving competencies.

RESULTS
To address the qualitative section of the study, the lesson observations, learners' activities during lessons, examples of learners' responses in pre-and post-test were discussed.Qualitative data was aimed to answer the third research question.To address the results of the quantitative data descriptive and inferential statistics were used where appropriate.Quantitative data was used to answer the first and second sub-research questions.

Qualitative Data
The activities of both the teachers and the learners were used to provide qualitative data about how these activities may have influenced the test scores.The third sub-research question was, as follows:

How did the classroom activities of both teachers and learners in POGIL classes compare to the lecture classes?
The report of the results shall commence with what was observed during the lessons.

Learners' activities during POGIL lessons
Table 4 was used to record the learners' activities to classify the level of engagement.As described in the data collection section the records were taken after every two minutes.Table 5 shows the results of the observation of one of POGIL lessons.The results from the other POGIL class were like these recorded on Table 5. Results from observation of POGIL lessons comply with expectations of POGIL lessons in terms of the learners' activities.
The learners were in the 'interactive' mode for 57% of the duration of the lesson and in the 'constructive' mode for 20% of the duration of the lesson.The 'active' mode occupied 7% of the lesson, while the 'passive and 'disengaged' modes occupied 14% and 3% of the There were few moments where the learners were in 'disengaged' mode.The learners were in the 'passive' mode for considerable time.These lessons were noisy as the learners deliberated the activities in the worksheets.

Teacher's activities during POGIL lessons
During POGIL lessons the teacher guided the learners by asking probing questions without telling the learners the answers.The teacher provided the worksheets and monitored the timeous completion of each activity.The teacher asked the spokespersons of each group to report their answers to the class.This was followed by discussion by the class to determine the correctness of the answers.The teacher moderated the discussion and only elaborated, where learners had disagreements or misconceptions.The teacher's activities comply with the expectations of POGIL facilitation.

Learners' activities during lecture lessons
The activities of the learners during the lecture lessons were classified using Table 4. Table 6 shows the results from one of the lecture classes.The second lecture class expressed similar results.We have used results from one of the classes for the purposes of discussion.
As indicated on Table 6 the 'interactive' and the 'constructive' modes witnessed 2% and 15%, respectively.The learners were in the 'active' and 'passive' mode for 28% and 60% of the duration of the lessons, respectively.The learners were in 'disengaged' mode for 5% of the duration of the lessons.The learners in the lecture lessons witnessed a large percentage of 'passive' and 'active' engagement as shown in Figure 3.

Teacher's activities during lecture lessons
During the lecture lessons the teacher explained all the concepts and gave notes to the learners who quietly paid attention.The teacher used examples and solved them for the learners who continued to copy in their notebooks.The teacher did all the talking with a few questions posed to the learners.The teacher did not pay much attention to the responses of the learners to their questions but continued to explain the concepts.The activities of the teachers were classified using Table 3 and showed that lecture method was appropriately used.

Quantitative Data
To answer the first and second sub-research question quantitative data were collected and analyzed as indicated in the data collection and analysis sections.
The first sub-research question asked:

What is the relationship between learners' problem-solving competencies in stoichiometry in
POGIL group compared to the lecture group before the intervention?
The second sub-research question asked, as follows: What is the relationship between learners' problem-solving competencies in stoichiometry in POGIL group compared to the lecture group after the intervention?

Descriptive statistics of pre-test results
To answer the first sub-research question descriptive statistics were used for both POGIL group and the lecture group in pre-test.
Even though all learners were taught stoichiometry using the lecture method in the previous grade, most learners in all the classes demonstrated 'novice' ideas in the pre-test.Some learners left the questions unanswered, others failed to identify the correct formula while the remainder could not recall the definition of a limiting reactant.Most learners failed to attempt the multi-step calculations.Table 7 shows the pre-test results for both groups.
No learner in all four classes demonstrated 'advanced' competency to solve stoichiometry problems, while a few demonstrated 'competent' competency.The percentage of learners with 'intermediate' competency was 5% and 4% in POGIL group and the lecture group, respectively.The percentage of learners with 'elementary' competency was 26% in POGIL group compared to 28% in the lecture group.The percentage of learners with 'novice' competency were 68% and 67% in POGIL and lecture groups, respectively.The results indicate that learners' problem-solving competencies in the pre-test in both groups were comparable.There was, therefore, no need to perform inferential statistics of the pre-test results.

Descriptive statistics of post-test results
To answer the second sub-research question descriptive statistics were done to assess the relationship between learners' post-test problem-solving competencies in stoichiometry in POGIL group compared to the lecture group after the intervention.
The post-test results suggest that learners in both POGIL and lecture classes improved in solving stoichiometry questions.Some of the learners managed to solve the simple and even some multi-step calculations.The improvement of POGIL classes, however, seemed higher than that of the lecture classes.Table 8 shows the post-test results for POGIL and lecture classes.The lecture classes evinced a high number of 'novice' ideas in all the questions compared to POGIL classes.The number of 'advanced', 'competent', and 'intermediate' ideas were higher in POGIL classes than in the lecture classes.

Questions 1 and 4a
Questions 1 and 4a were level I questions asking learners to recall a definition or complete single-step calculation.In POGIL group in question 1 there was only one 'novice' response (2%) compared to 27 responses (44%) in the lecture group.In question 4a there were six 'novice' responses (13%) in POGIL group compared to 37 responses (60%) in the lecture group.The rest of the responses were acceptable 'elementary' knowledge in solving the level 1 question.It implies that in the level 1 questions learners in POGIL classes performed better than those in the lecture classes.

Level II Questions
Questions 3b, 6a, 6b, and 6c were level II requiring responses through two-step calculations.The results from the level IV questions suggest that the learners in POGIL group had better problem-solving competencies than their counterparts in the lecture group.Overly in the post-test, the learners in POGIL group showed better problem-solving competencies in solving stoichiometric problems than the learners in the lecture group.
The null hypothesis was, therefore, rejected since the results suggest that there is a relationship between the learners' problem-solving competencies and the teaching approach.In this case, POGIL method developed higher problem-solving competencies than the lecture method.The learners in POGIL group solved both simple and complex questions, while the learners in the lecture group had difficulties in solving both simple and multi-step calculation questions alike.

ANOVA Tests
The data from the post-test verified some distinctions in problem-solving competencies of POGIL and the lecture groups.For that reason, ANOVA tests were performed for the post-test results of the lecture group compared to POGIL group.The purpose of the ANOVA test was to find out if teaching approach statistical significantly affected the learners' competencies in stoichiometry.Table 9 shows the results of the effect of the change in the teaching method as measured in the learners' responses to the post-test.
The results, as shown in Table 9, indicate all p-values lower than alpha (0, 05) in all the questions.Such results confirm that there was a statistical difference in the learners' problem-solving competencies between the two groups.Further analysis indicates that in all the questions, the averages, and the sums of POGIL group were higher than the lecture group.The higher the test scores the higher the competencies, as shown in Table 5.Therefore, the problem-solving competencies of learners in POGIL group were statistically significantly higher than learners in the lecture group.

DISCUSSION
In this paper, we found out that the lecture method, which is widely used by teachers in secondary schools in SA and universities alike, does not pay attention to the active engagement of learners.Some reasons for  (Govender, 2015).Failure of DoBE (2020) to address the concerns of the teachers and lecturers impedes the transformation of teaching approaches from traditional to active.When teachers fail to pay attention to the active engagement of learners, they will assume that the learner's engagement during the lecture method whilst they may be disengaged or passively attending class.This lecture method encourages rote learning and does not lead to the understanding of concepts.The lecture method may allow the teacher to properly organize the topics and develop concepts in a logical manner but is ineffective when application of facts or critical thinking are required such as in science (Miller et al., 2013).
Analysis of the teachers' and learners' activities in POGIL group in the current study suggests the promotion of active engagement of learners.This agrees with the findings from (Strachan & Liyanage, 2015).Active learning has a positive effect on the cognitive development of learners as they invent concepts and develop understanding (Simonson, 2019).
The learners in the lecture classes spent most of the duration of the lessons in the 'Passive mode' while those in POGIL classes spent most time in the 'Interactive mode'.This agrees with the findings from (Miller et al., 2013).The reader should take note that the learners in POGIL group were in the 'passive' mode of engagement during the times when they listened to the 'reader' and to the teachers' instructions.The learners in POGIL classes were occupied with the class activities in their groups for the greater part of their lessons.These activities may have been the reason for the higher problem-solving competencies.This agrees with the findings in previous studies by Moog and Spencer (2008) and Simonson and Shadle (2013).On the other hand, the learners in the lecture group were in the 'passive' mode when they listened to the teacher.These learners did not have moments to listen to each other but only to the teacher.This agrees with the study by Govender (2015).
The current research witnessed an increase in the problem-solving skills of learners in stoichiometry after receiving lessons using both POGIL method and the lecture method.This explains some degree of effectiveness of lecture method.POGIL group showed statistically significantly higher problem-solving competencies than lecture group.This corroborates the previous findings by Omoniyi and Torru (2019).
The learners in POGIL group solved both simple and complex questions, while the learners in the lecture group had difficulties in solving both multi-step calculations and simple questions alike.As a result, the learners in POGIL group improved motivation as they actively and happily discussed the worksheets and improved achievement as indicated by the higher test scores.This agrees with the findings by Santoso et al. (2023).
Both the lecture and POGIL classes had an equal duration of four hours during which the same number of concepts were covered.This indicates that POGIL is not time-consuming in terms of lesson delivery.This finding disagrees with the findings by Mamombe et al. (2021), that POGIL is time consuming.In the current study we argue therefore, that POGIL is timeous during preparation of the worksheets and not during delivery of the lessons (Douglas, 2011).
The learners in POGIL classes were noisy.This agrees with the findings by Simonson (2019).The noise of POGIL classes were, however, constructive since the learners were engaged in the 'interactive' mode solving the worksheets.The learners in POGIL classes learned much more than those in the lecture class.The quietness of the learners in the lecture classes did not translate into problem-solving competencies.These learners lacked the skills to solve stoichiometry even though they seem attentive during the lecture lessons.This agrees with the findings by Miller et al. (2013).

CONCLUSIONS & RECOMMENDATIONS
The results of pre-and post-test indicate that the use of POGIL to teach stoichiometry produces statistically significantly higher problem-solving competencies as compared to using the lecture method.POGIL method also produces higher test scores as indicated by the higher sum and the averages of their test scores as compared to learners in the lecture group.The learners in POGIL classes were actively engaged most of the time and solved both the low-order and the high-order stoichiometry questions during the lessons and in the tests.This may have resulted in better problem-solving competencies in POGIL group compared to the lecture group.We conclude that POGIL rather than the lecture method is more effective in teaching stoichiometry, which is a complex abstract topic.The use of learnercentered teaching methods such as POGIL may be effective in increasing problem-solving competencies in learners.The use of POGIL in teaching stoichiometry is recommended since this approach elucidates and clarifies abstract and complex concepts.Malcolm, S. A., Mavhunga, E., & Rollnick, M. (2019)

Figure 1 .
Figure 1.ICAP theory of active learning(Chi et al., 2018) duration of POGIL lessons, respectively.During POGIL lessons the results indicate a large percentage of 'interactive' and 'constructive' engagement as clearly shown on Figure 2. The learners were actively engaged for 74% of the duration of the lesson.

Table 1 .
Structure of questions in pre-& post-test Q&L Bloom's cognitive levels Skills assessed 1-I Remembering Identify correct formula.Substitute in the formula, identify the correct atomic mass.2-III Analyze & apply Choose correct formula & substitute appropriately.Link two formulae using mole ratio.3a-III Analyze & apply Choose correct formula & substitute appropriately.Link two formulae using mole ratio.

Table 2 .
Observation schedule for teachers' activities

Table 3 .
Observation schedule for learners' activities

Table 4 .
Classification of responses to questions in tests

Table 5 .
Results of observation of a POGIL lesson

Table 6 .
Results of observation of a lecture lesson

Table 7 .
Pre-test results