Impact of inquiry-based labs on junior chemistry students’ conceptual understanding in high schools

Thesis Abstract

Inquiry-based laboratory experiences have the potential to transform junior chemistry learners’ conceptual understanding by centering inquiry, experimentation, and evidence-based reasoning within high school science classrooms. This study investigates how structured inquiry-based labs influence students’ grasp of core chemical concepts, with particular emphasis on the linked development of conceptual knowledge and scientific thinking skills among 9th and 10th grade students. The aim is to determine whether deliberate integration of inquiry-based practices enhances conceptual understanding beyond traditional cookbook laboratories, and to identify mechanisms by which such improvements occur. Specific objectives include (1) evaluating changes in conceptual understanding of atomic structure, bonding, reaction kinetics, and stoichiometry; (2) examining shifts in science process skills such as hypothesis formation, experimental design, data interpretation, and argumentation; (3) comparing the effects across gender and prior achievement strata; (4) exploring teacher implementation fidelity and its relationship with student outcomes; and (5) deriving practical implications for curriculum alignment and professional development. A quasi-experimental design will be employed in two matched high schools over one academic semester. The population comprises junior chemistry students enrolled in compulsory chemistry courses with similar demographic profiles. A total sample of 320 students will be recruited, with 160 students assigned to the experimental group receiving a sequence of eight inquiry-based labs, and 160 to the control group continuing standard confirmatory labs. The experimental protocol will be guided by the principles of inquiry-based learning and aligned with constructivist theory, drawing on Piagetian conceptions of knowledge construction and Vygotskian social constructivism to frame the expected learning processes. Data collection instruments will include (a) a validated Conceptual Chemistry Test (CCT) administered as a pretest and posttest to measure gains in core concepts; (b) a Science Process Skills Inventory (SPSI) to assess procedural and reasoning abilities; (c) a student attitude towards science survey to capture motivational dimensions; and (d) classroom observation rubrics to monitor fidelity of implementation. Additionally, think-aloud interviews with a purposive subsample of 40 students and teacher reflection journals will be conducted to illuminate cognitive processes and instructional dynamics. Data analysis will proceed in several stages. Descriptive statistics will profile baseline equivalence and post-intervention distributions. Inferential analyses will utilize ANCOVA to compare posttest CCT scores between groups while controlling for pretest performance, and multilevel modeling to account for clustering at the class level. Regression analyses will examine the moderating effects of prior achievement and fidelity of implementation on learning gains. The SPSI scores will be analyzed with repeated-measures ANOVA to detect within-subject changes over time. Qualitative data from interviews and teacher journals will undergo thematic analysis to extract patterns related to cognitive engagement, problem-solving strategies, and classroom discourse, triangulated with observation data to explain observed quantitative effects. Expected findings include statistically significant improvements in conceptual understanding for the experimental group, with larger gains in topics most amenable to inquiry, such as reaction kinetics and bonding, accompanied by enhanced science process skills and more sophisticated scientific argumentation. It is anticipated that higher implementation fidelity will correlate with larger effect sizes, and that positive shifts in student attitudes will mediate part of the relationship between inquiry-based instruction and learning outcomes. The study contributes to knowledge by providing robust empirical evidence on the effectiveness of inquiry-based labs in enhancing junior students’ chemistry conceptual understanding, delineating the interaction between inquiry practices, cognitive processes, and achievement, and informing policy decisions regarding curriculum design and teacher professional development. The principal conclusion is that well-structured, fidelity-monitored inquiry-based lab sequences produce meaningful conceptual gains, particularly when aligned with formative assessment and guided scaffolding. Recommendations include scaling up inquiry-based lab modules with explicit rubrics for assessment, targeted professional development emphasizing inquiry design and discourse, and further research into long-term retention of conceptual understanding and transfer skills across chemistry topics.