Comparative effect of two problem-solving instructional startegies on students' achievement in stoichiometry
The study aimed to investigate the comparative effects of Selvaratnam-Fraser and Ashmore et al Problem-Solving instructional strategies on Advanced Level students’ achievement in Stoichiometry. The population of the study was drawn from 15 high schools in Gweru urban District of the Midlands province in Zimbabwe. Using convenience sampling techniques 8 high schools with n=525 Advanced Level Chemistry learners and 8 teachers participated in the study. Four schools formed the experimental group (n=250) and the other four schools formed the control group (n=275). The study employed a quasi-experimental design with a non-equivalent control group approach consisting of pre-and post-test measures. Intact classes participated in the study as it was not possible to randomly select participants for the study. The principal instruments for data collection were standardized achievement Tests in stoichiometry that were aligned to the Zimbabwe Schools Examinations Council A’ level National syllabus for chemistry. The tests were written by all participants at pre- and post-stages of the experiment. The problem-solving instruction was implemented in four experimental schools by the respective chemistry teachers who had been trained as research assistants in the use of the problem-solving strategies in chemistry teaching. The four control schools were also taught by their teachers using the conventional lecture method. Analysis of Covariance (ANCOVA) was used to analyze data. The results of this study indicated that the participants in experimental schools performed significantly better than participants in control schools on certain aspects of problem-solving performance. The Scheffe’s post- hoc test indicated that students taught using the Ashmore et al problem-solving instructional strategy performed better than those taught with the Selvaratnam-Fraser problemsolving strategy. Chemistry teachers are therefore strongly recommended to use problem-solving instructional strategies in their classes to facilitate students’ problem-solving performance. The study further recommends that pre-service chemistry teachers be properly trained in instruction that promotes problem-solving and how to effectively implement problem-solving instruction. Furthermore, in-service training for practicing chemistry teachers is recommended so that they can embrace the skills of the problem-solving strategies for effective implementation of the strategies in teaching chemistry.