This study investigated the effects of chemical concept understanding level on students’ achievement in biochemical topics (photosynthesis, respiration, diffusion and osmosis, carbohydrates, protein, fats and enzymes) in some selected secondary schools in Delta State of Nigeria. The study made use of mixed method research approach. Quantitatively, the design of the study was quasi experimental non-randomized pre-test and post-test control group design. A case study Embedded Design was adopted to take care of the qualitative aspect of the mixed method study. Kuder-Richardson formula 20 (K-R20) was used to calculate the reliability coefficient of the test. The internal consistency of reliability co-efficient was calculated to be 0.76 that made the instrument to be accepted as reliable for the study. The population of this study consisted of all senior secondary (II) biology students in the twenty (25) local government areas of Delta State of Nigeria. Six secondary schools randomly selected from the three senatorial districts of the State were used for the study, with three (3) schools for experiments specially taught with emphasis on both ideas (concepts) and skills, problem-based interactive learning ensuring concept connections and the other three (3) for control groups. Intact classes were used for both groups. The intact sample was made up of five hundred and ninety two (592) students for the quantitative study; while two teachers and four students were purposively sampled for the qualitative aspect of the study. Four (4) research questions were raised and answered and four (4) null hypotheses were formulated and tested at 0.05 level of significance. The research instruments used were the Test of Students Understanding of Chemical Concepts (TOSUCC), Biology Achievement Test (BAT) which measured achievement in biochemical topics and Interview Schedules for both teachers and students. The quantitative data collected were analysed using Analysis of Covariance (ANCOVA) for the hypotheses and mean ratings for the research questions; and the qualitative data were analysed by coding and themes generation and interpretations. Findings show that the experimental group performed better than the control group in the biochemical topics. An effect size of Cohen`s d equal to 0.996 was determined from the mean scores and standard deviations of the experimental and control samples for the study. Therefore, the experimental group had better achievement because determined effect size seemed large enough in favour of the treatment group. No significant interaction effects of gender and location on students` level of achievement in both experimental and control groups were established by the study. The teachers in particular should use the outcome of this study to improve on their teaching, emphasizing on concept understanding in their teaching and prior learning/knowledge or pre – requisite concepts. This is because certain chemical concepts are required before the teaching of the main topics (Biochemical topics in this case). In other words, this study recommends that secondary school biology and chemistry teachers should teach for concept understanding, topics that are related to the new topics before teaching the topics. / Science Education / Ph. D. (Science Education)

Tidigare forskning visar att det knappt finns forskning om vilken undervisningsform som lämpar sig för implementering för yngre elever i kemi. Frågan om att hitta en undervisningsmetod som ökar elevernas prestationer i kemi är en utmaning i det moderna skolsystemet. Fortsättningsvis visar forskning att laborationer inte var en lämplig undervisningsform som introduktion för ett naturvetenskapligt lärande i de lägre åldrarna, men det saknas gedigna empiriska bevis som stödjer detta påstående. Därför, i den föreliggande studien, undersöks laboratorie- och traditionella undervisningsmetoder på ämnet vattnets aggressionsformer. Denna studie involverade 50 deltagare som är grundskoleelever i årskurs 3. Data samlades in med ett för- och eftertest. Resultatet av denna studie visade ingen uppenbar skillnad i testpoängen mellan jämförelse- och experimentgruppen. Resultaten visade även att den laborativa undervisningsmetoden gav ett bättre utfall på elevernas förståelse på mikronivå. Till skillnad från experimentgruppen kunde den traditionella undervisningen nämna vattnets fasomvandlingar mycket mer än vad laboratorieundervisningen kunde. Avslutningsvis, visade studien ingen tydlig skillnad i testpoängen mellan jämförelse- och experimentgrupp. / Previous research shows that there is hardly any research on teaching methods suitable for implementation for younger students in chemistry. The issue of finding a teaching method that increases student achievement in chemistry is a challenge in modern school systems. Research shows that laboratory work was not a suitable form of teaching as an introduction to chemistry at younger ages, but there is a lack of solid empirical evidence to support this claim. Therefore, in the present study, the laboratory and traditional teaching methods are examined on the topic of water's state of matter. The research involved fifty participants that are primary school students in grade 3. Data was collected using a pre-test and post-test. The results also showed that the laboratory teaching method improved students' understanding at the micro-level. Unlike the experimental group, the traditional teaching could mention water phase transformations much more than the laboratory teaching could. The outcome of this study showed no evident difference in the test scores between the comparison and experimental groups.