Constructivism, despite its varied interpretations, serves as the core learning theory for this study. It emerged as a response to the limitations of the stage model of cognitive development, stressing the importance of enabling students to construct and comprehend concepts rather than simply receiving transmitted information ( Allen et al., 2002 ; Osborne, 1996 ). According to Hein (1991) , individuals actively generate knowledge, perceiving learning as a student-centered process where learners make sense of concepts through engagement and experience ( Tetzlaff, 2009 ). This perspective encourages learners to use their personal experiences and perspectives to interpret concepts, moving away from rote memorization and teacher-centered approaches ( Tan, 2017 ).

Constructivism highlights the importance of active participation, constructive and complex learning processes, contextual understanding, collaborative learning environments, and reflective thinking ( Tetzlaff, 2009 ). Knowledge is constructed through interactions with the environment and the meaningful processing of new information ( Hein, 1991 ; Taber, 2011 ). Jones and Brader-Araje (2002) assert that constructivism fosters student ownership of learning, positioning teaching as a facilitative process that supports the construction and reconstruction of knowledge. This approach emphasizes the significance of learners’ cognitive structures and their active role in making sense of new experiences ( Taber, 2011 ).

In summary, constructivist learning theories are valued for their focus on students’ active roles in constructing meaning, the importance of meaningful learning experiences, and active learner engagement ( Jones & Brader-Araje, 2002 ). Luong & Kim (2022) characterize constructivism by key elements such as active meaning-making through interaction, cognitive engagement through challenges, collaboration to construct meaning, and reflection to refine understanding in authentic contexts as shown in Figure 1.

Redox reactions have been historically explained through four models: the oxygen model, the hydrogen model, the electron model, and the oxidation number model, which are essential for contemporary chemistry education ( Adu-Gyamfi et al., 2019 ).

1) Oxygen Model: Initially proposed by Stahl’s phlogiston theory and later refined by Lavoisier, this model describes oxidation as the combination of oxygen with other elements.

2) Hydrogen Model: Defined by Liebig, this model describes oxidation as the loss of hydrogen atoms.

3) Electron Model: Based on Faraday’s ion theory, this model explains oxidation as the loss of electrons and reduction as the gain of electrons.

4) Oxidation Number Model: Introduced by Lewis, this model uses shared electron pairs in covalent bonds to determine oxidation states, with oxidation involving an increase in oxidation number.

Balancing redox reactions can be achieved using the half-reaction method or the oxidation number method as illustrated in Figure 2. In acidic media, oxygen atoms are balanced with H₂O, and hydrogen atoms with H⁺. In basic media, OH^- ions neutralize H⁺ ions to form H₂O molecules ( Qiang et al., 2003 ).

Shulman (1986) introduced the concept of Pedagogical Content Knowledge (PCK), which integrates subject matter expertise and teaching skills, enabling teachers to effectively convey content to students. PCK involves understanding the best ways to present content, catering to diverse student needs and abilities ( Padilla & Van Driel, 2011 ).

Components of PCK

Wongsopawiro et al. (2017) . PCK evolves from teaching experience, knowledge of specific issues, and familiarity with curriculum materials ( Padilla & Van Driel, 2011 ).

Effective Teaching with PCK

PCK helps teachers adapt content for diverse students, aiding meaningful knowledge construction ( Mishra & Koehler, 2006 ). Effective teachers possess strong PCK, enabling them to analyze students’ understanding, create exploratory activities, and facilitate discussions ( Adu-Gyamfi et al., 2018 ).

Numerous studies have highlighted the conceptual challenges students face in learning redox reactions ( Adu-Gyamfi et al., 2018, 2019 ). Sensory learners particularly struggle with theoretical and equation-based explanations in chemistry ( Felder, 1993 ). Students often find it difficult to transition between macroscopic and microscopic understandings of chemical concepts and to grasp that oxidation and reduction reactions occur simultaneously ( Österlund & Ekborg, 2009 ).

The sequence in which topics are presented in textbooks can also contribute to these difficulties, as some concepts do not build sufficiently on each other ( Ali, 2012 ). Additionally, while students can identify reducing agents easily, they often struggle to recognize oxidizing agents, sometimes incorrectly identifying compounds like water as the oxidizing agent ( Österlund & Ekborg, 2009 ).

Learning involves cognitive, physical, and affective processes, with depth referring to understanding, manipulating, applying, and communicating knowledge ( Matorevhu, 2022 ). Constructivist theories emphasize active student involvement in building meaning through interaction with texts, the environment, and social contexts ( Wilson & Peterson, 2006 ).

Constructivist instructional strategies that emphasize interactivity and engagement are most effective for facilitating behavior change ( Allen et al., 2002 ). Teaching strategies should be diverse, including guided conversation, group work, and problem-based learning, to support effective learning. Adapting teaching tactics to fit students’ learning strategies can reduce difficulties and improve understanding ( Adu-Gyamfi, 2016 ).

The participatory approach involves participants in planning, executing, reflecting on activities, and evaluating outcomes, fostering local content inclusion in lessons ( Greenwood, Whyte, & Harkavy, 1993 ). Participatory learning emphasizes teamwork and group involvement, enhancing pedagogical knowledge and assessment expertise ( Adu-Gyamfi et al., 2019 ).

Participatory learning bridges theory and practice through practicality, collaboration, reflection, and intentionality ( Trauth-Nare & Buck, 2011 ). It values all opinions, promotes collaboration, and prevents instructional planning from being solely developer-driven ( Johnson, 2013 ). This method fosters peer learning, enhances understanding, and generates new ideas for lesson plans, leading to higher satisfaction and effective concept learning ( Ainscow, 2005 ; Chan, 2010 )

Since the early 1980s, the Newman approach to challenge analysis has gained popularity. This method involves interviewing individual students and categorizing their challenges based on the Newman hierarchy. In Malaysia, the Newman method found that over 90% of challenges by Grade 7 students were related to understanding or transformation ( Faulkner & Kent, 2001 ).

Participatory learning, emphasizing the selection of strategies and reflection for effective instruction, aligns with constructivist learning theory, which posits that knowledge is constructed through interaction with concepts, reflection, and the environment ( Pain et al., 2011 ; Hein, 1991 ; Lowenthal & Muth, 2008 ). Effective instruction combines student-centered and teacher-directed approaches, with social interactions playing a crucial role in enhancing learning ( Taber, 2011 ; Tetzlaff, 2009 ). Understanding and preventing challenges is vital, with Newman identifying five types: reading, comprehension, transformation, process skills, and encoding challenges ( White, 2010 ). The Newman procedure aids teachers in identifying and correcting these challenges ( Sumule et al., 2018 ). Electrochemistry, a critical topic in high school chemistry, includes oxidation-reduction processes, redox titrations, electrochemical cells, and corrosion, posing significant challenges for pre-service science teachers. Common challenges and misconceptions include difficulties in writing chemical equations, understanding oxidation and reduction half-reactions, and balancing redox reactions involving H₂O, H⁺, and OH^-, often due to language barriers, rote learning, and ineffective instructional strategies. While traditional lecture-based methods predominate, innovative approaches like problem-based learning (PBL) show promise for enhancing comprehension and retention of electrochemical concepts.

The study focused on six Colleges of Education in Ghana, categorized into five zones: AshBa, CentWest, EaGa, Volta Region, and Northern Region. These colleges, designated as science colleges, include General Chemistry in their curriculum, which covers topics such as redox reactions. The participants of the study were Level 200 students, as redox reactions are taught during the second semester of their second year.

The accessible population consisted of 1211 pre-service teachers who were studying Chemistry as an elective. These students were also majoring in various subjects, including Primary Education, JHS Education, Early Grade Education, and Home Economics Education. Enrolment figures were obtained from the Academic Affairs offices of the selected colleges and confirmed by chemistry tutors.

The entire accessible group of 1211 pre-service teachers were selected as the sample through the stages below:

Stage One: Purposive sampling selected six colleges from the 46 Colleges of Education in Ghana, affiliated with the University A and offering chemistry as an elective.

Stage Two: Purposive sampling selected specific levels from the chosen colleges, focusing on those studying the mole concept and redox reactions.

Stage Three: Purposive sampling selected two respondents from each college, for interviews based on test results, choosing those who scored extremely high or low marks ( Garbo et al., 2023 ).

The results are shown in Table 1 below:

Source: Colleges’ Academic Affairs Offices (2023).

Primary research instruments: tests, questionnaires, and interviews.

Reduction-Oxidation Reaction Diagnostic Test (RORDT)

The Reduction-Oxidation Reaction Diagnostic Test (RORDT) is a standardized assessment designed to identify and address difficulties in understanding redox reactions. This test evaluates participants’ struggles with the concept and suggests potential remedies. The scoring of the RORDT is consistent with the method used for end-of-semester exams at the Institute of Education, University A.

The development of the RORDT involved a thorough process, including planning, preparation, review, revision, and validation to ensure alignment with the chemistry curriculum at the Colleges of Education ( Kubiszyn & Borich, 2024 ). To guarantee its consistency and effectiveness in measuring the intended constructs, the test was piloted with a sample of pre-service teachers.

The questionnaire, adapted from the Newman Hierarchical Challenge Model, was designed for data collection during the quantitative phase of the study. It included both open-ended and closed-ended questions to measure specific variables, as outlined by Baburajan et al. (2020) . The model was tailored to fit the context of Ghanaian Colleges of Education.

The questionnaire was divided into three sections: the first gathered demographic information, the second focused on items related to redox reactions, and the third sought pre-service teachers’ suggestions on effective teaching methods as shown in Table 2 . A 5-point Likert scale was utilized for its proven reliability and validity in analysis, as supported by de Rezende and de Medeiros (2022) and Sullivan & Artino (2013) . The increased number of points on the scale enhances its reliability and validity.

Organization of the Research Instrument

Semi-structured interviews were conducted to gather detailed and in-depth responses from pre-service teachers. These interviews, lasting between 15 and 20 minutes, focused on predetermined questions aligned with the study’s research questions ( Lapan et al., 2011 ). The sessions were designed to be flexible and interactive, allowing for the capture of rich, contextually relevant data ( Adams, 2015 ). The data collected were manually transcribed and subsequently verified with the respondents to ensure accuracy.

Test Validity and Reliability: The KR-20 coefficient was used to assess reliability, with a value of 0.70 indicating strong internal consistency ( Pallant, 2020 ). Tests were reviewed by experts and piloted to ensure validity.

Questionnaire Reliability: Cronbach’s alpha coefficient for the questionnaire was 0.808, indicating good reliability ( Jayaraman & Ghazali, 2023 ; Merriam & Tisdell, 2009 ).

Administered to a sample of 30 pre-service teachers to identify and assess challenges, with reliability checked using Cronbach’s alpha coefficients of 0.808 and 0.871 for the questionnaire and test, respectively.

Data were collected from 1200 pre-service teachers at six colleges. Procedures included obtaining consent, briefing participants, and ensuring accurate data collection through tests, questionnaires, and interviews.

Data from interviews were transcribed and coded for accuracy. Respondent validation ensured data authenticity ( Creswell & Miller, 2000 ).

Quantitative data were gathered and analyzed using SPSS. Various statistical techniques (mean, standard deviation, factor analysis, regression) addressed research questions and tested hypotheses regarding challenges in learning redox reactions.

Ethical integrity was maintained by obtaining permissions, ensuring voluntary participation, and safeguarding anonymity and confidentiality ( Sharma et al., 2022 ).

Research Question One: Prevalent Challenges and Misconceptions Among Pre-service Science Teachers in Understanding and Balancing Redox Reactions

Objective 1:

The results, summarized in Table 3 , provided insights into common student challenges in learning redox reactions based on the collected data.

Field survey, Michael Owusu (2023).

Summary of Findings from Table 3 .

Students’ Agreement on Challenges:

Students reported difficulties with several aspects of redox reactions:

Students’ Disagreement on Challenges:

Students disagreed with statements about:

Common challenges included challenges with reading and interpreting redox reactions, misconceptions about the role of oxygen, and difficulty in identifying the correct models and showing working steps.

Interviews further elaborated on these challenges.

S1 In redox reactions, I struggle to understand what the question is asking, particularly whether it’s about the loss or gain of hydrogen, oxygen, electrons, or the increase or decrease in oxidation number. Aside from that, I think I’m okay.

S2 I know the four models of redox, but I have difficulty identifying which to use when solving questions involving these models, which I think is my biggest problem with redox.

S3 When a question asks for a half-reaction equation in redox, I always have difficulty showing the working steps for writing the half-reaction. Sometimes I guess correctly, but I can’t explain how I arrived at it.

S4 Regarding redox reactions, I don’t remember what the teachers taught us in high school or what the topic entails, especially about oxidizing and reducing agents.

S5 I have difficulty figuring out what to use when solving questions involving the four oxidation-reduction models. It’s not my fault; we didn’t have a chemistry teacher in high school until a National Service Person taught us in our final year, but not in detail.

S6 I wasn’t taught redox reactions in high school, so I relied on my own readings. I first heard about the four redox models here in college. Therefore, I struggle with identifying which model to use for solving questions.

S7 I believe oxygen is always present in redox reactions. Whenever I read a question and don’t see oxygen, I don’t recognize it as a redox reaction question.

S8 Some challenges I make in redox reactions include difficulty showing the working steps for writing half-reactions and trouble reading the problem to understand what the question demands.

S9 My only challenge in redox is showing the step-by-step process for writing half-reactions.

S10 The challenges I make in redox reactions stem from difficulties reading the problem and understanding what the question demands. I don’t really grasp the meaning when I read the question.

S11 For me, redox is a very complicated topic in chemistry because I didn’t know that reduction and oxidation reactions happen simultaneously; I thought they occurred at different times.

S12 Reading the redox question for understanding isn’t a problem for me. The issue is identifying what’s needed to solve the problem, which is my biggest challenge.

Summary of Interview Responses and Categorizations

Interview Responses:

Pre-service teachers reported:

These findings are consistent with the quantitative data results.

Categorizations of Challenges

Objective 2: Identify possible categorizations of challenge in learning redox reactions.

Method: Responses were analyzed using exploratory factor analysis (EFA), suitable for identifying structural patterns in challenge categorizations.

Approach: Principal axis factor analysis with Oblimin (oblique rotation) was used for examining the component correlation matrix.

Data Analysis: EFA was conducted on 14 items assessing challenge made by students in understanding redox reactions.

Extraction Method: Principal Component Analysis.

Summary of Exploratory Factor Analysis and Challenge Impact Analysis

Exploratory Factor Analysis (EFA):

Challenge Impact Analysis

Objective 3:

Objective: Identify which challenges significantly contribute to difficulties in learning redox reactions.

Method: Responses on challenge impact were analyzed using multiple regression, which assessed the influence of various predictor challenges (comprehension, transformation, process skills, encoding) on the criterion variable (redox reactions).

Assumptions Checked: Normality and linearity assumptions were verified prior to regression analysis (see Figure 3).

Summary of Regression Analysis Preparation

a. Predictors: (Constant), REDOXP, REDOXTRANS, REDOXCOM, REDOXE; b. Dependent Variable: REDOX.

a. Dependent Variable: REDOX; b. Predictors: (Constant), REDOXP, REDOXTRANS, REDOXCOM, REDOXE.

a. Dependent Variable: REDOX. Redox = 19.489 + 0.343 (REDOXCOM) + 0.233 (REDOXTRANS) + 0.022 (REDOXE) + 0.499 (REDOXP)

Summary of Regression Analysis Results

Influence of Challenges: Process skills challenges are identified as the most significant predictor of difficulties in learning redox reactions.

According to Table 10 , the challenges have a weak negative and statistically insignificant effect on learning redox reactions (r = −0.026, p > 0.05).

Responses from the oral interviews regarding the extent to which challenges affect pre-service teachers’ learning of redox reactions were gathered through discussions with them. The summarised responses are as follows:

S1 I consistently make mistakes with my final calculations and the overall balanced equation because I struggle to understand what the question is asking, especially regarding the loss or gain of hydrogen, oxygen, electrons, and changes in oxidation numbers.

S2 Although I am familiar with the four redox models, I have difficulty identifying which one to use when solving problems involving these models.

S3 I frequently get the overall balanced equations incorrect. I also face challenges in demonstrating the working steps needed to write half-reactions for redox equations.

S4 I lack interest in redox reactions and don’t recall anything about oxidizing and reducing agents.

S5 I rarely practice redox exercises independently because I have trouble determining which methods to use for solving questions related to the four redox models.

S6 I rely on my limited knowledge to solve redox questions, as I struggle to identify the correct approach for the four redox models.

S7 I don’t believe challenges negatively impact my learning of redox reactions. Although I understand that oxygen is typically present in redox reactions, I disregard questions without oxygen as not being related to redox reactions.

S8 I often make challenges with the overall balanced equations due to difficulties in showing the working steps for writing half-reactions.

S9 My difficulty in demonstrating step-by-step working for half-reactions leads to incorrect overall balanced equations.

S10 My results are often incorrect because I have trouble understanding what the problem is asking.

S11 I struggle to identify both oxidation and reduction agents in a single reaction because I mistakenly thought reduction and oxidation occur at different times.

S12 Although my final equations might be correct, they are often unbalanced due to my general inability to balance chemical equations.

Summary of Interview Findings and Remedies

Interview Findings: Most pre-service teachers struggled with identifying appropriate methods for solving redox reaction questions and showing working steps for half-reactions. These challenges affected their ability to write final balanced equations. This contrasts with quantitative data, which did not show a significant impact of these challenges on learning.

Research Question Two: Innovative Teaching Strategies to Address and Mitigate Challenges and Misconceptions in Learning Electrochemistry.

Remedies:

Objective: To gather suggestions on how to improve the teaching of redox reactions.

Method: An open-ended and closed-ended questionnaire was distributed to 1200 students, with 1197 responding.

Analysis: Responses were categorized and analyzed for frequency and percentage to identify common suggestions for improving redox reaction teaching.

Findings: Detailed in Table 11 .

Field survey, Michael Owusu (2023).

Summary of Remedies

Remedies for Challenge in Learning Redox Reactions ( Table 11 ).

Laboratory Work: Recommended by 301 respondents (25%) as it enhances understanding more effectively than theoretical instruction alone.

Pedagogical Content Knowledge: Suggested by 275 students (23%) to ensure tutors have a strong grasp of teaching methods, addressing the observed lack of expertise among SHS chemistry teachers.

Peer Collaborative Work: Recommended by 143 students (11.9%) to facilitate learning through idea sharing and better comprehension.

Small Group Work: Suggested by 141 students (11.8%) to foster respect and improve understanding based on positive experiences.

Comprehensive Teaching: Advised by 104 students (8.4%) to ensure that topics like ‘balancing chemical equations’ are thoroughly taught, rather than assuming prior coverage.