Concreteness of energy and bonding concepts in 9th grade chemistry–examining learning among high and low achievers

Concreteness fading was applied in a curricular unit on energy changes in chemical reactions. Students explored bond breaking and formation by physically interacting with magnets, observing these processes through computer simulations and diagrams, and applying them to chemical equations. The participants included 36 ninth graders from a regular public school and 56 from a science magnet school. Conceptual knowledge was assessed using questionnaires administered before and after the unit, and 11 students were interviewed to support the quantitative findings.We observed significant pretest-to-posttest gains among both groups, with magnet school students achieving college-level averages. Regular school students showed smaller gains on items related to the definition of bonds or those involving purely symbolic chemical representations. However, both groups made similar progress in understanding macro-scale observations of energy change and in applying bonding concepts to nano-scale visual representations. Consistent with other studies, our findings indicate that while concreteness fading is an effective teaching strategy, it does not reduce the performance gap between high and low achievers. Interviews suggest that this gap stems from the difficulty low achievers face in adopting bonding concepts as visual and physical representations are phased out.