Students' Understanding of Combustion: A Cross Age Study

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This study used a cross-age design to investigate Taiwanese students' understanding of combustion and how they apply their knowledge in a variety of practical situations. The study used nine content and six application questions to investigate 631 students' understanding of combustion ranging from 6th grade to university students. For example, three application questions were used to investigate the students' knowledge application in closed systems, including how/why should people act when a fire accident occurs in a room (Q13), why does a lighted candle extinguish in a bottle (Q14), and how/why do two lighted candles of different lengths burn in a bottle (Q15)? Students' conceptions about how combustion occurs in semi-closed and closed systems, which have very important real world consequences have not been studied in detail and science instruction rarely mentions the situation.

There are two main findings. First, the older students, in general, had better understanding of content knowledge than the younger students. For example, the younger students could not recognize water as one of the products in a combustion reaction (19% vs. 91% in the older students). Second, the students' performance on the application questions, though requiring similar knowledge to solve, varied considerably. For example, most of the answers about the fire accident (Q 13) were correct regardless of their ages. On the question about a single candle experiment (Q 14), the students' performances were uniformly low regardless of age.

As students had problems with the conceptions of combustion, the study has implications for science teachers and science teacher educators. Specifically, teachers can utilize the findings to develop different instructional strategies to overcome the alternative conceptions. The findings can benefit teachers giving similar instruction to students and curriculum developers modifying current curriculum materials.


Washington, DC

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