Abstract
The purpose of this study was to explore intermediate students' conceptions about evaporation , condensation and boiling, and to identity the keypoints to the students' learning of these concepts. An open-ended written test (N=758) and multi-choice test (N=760) containing the same tasks were administered to intermediate students in the Taipei area. The results of these two tests show that students had better understanding on the evaporation concept than condensation concept. When exploring the phenomena of evaporation and condensation in an open and closed system, the majority of the students had a clear understanding on the evaporation of water, but had no idea about the change of water vapor into water drops which occurred in the second half of the systems. In addition to that, students were not able to differentiate the formation of tiny water drops in an open and closed system. In the open-ended written test only 26.6% of the students responded that the matter inside the bubbles formed during boiling is water vapor, while 57.6% of the students completed the multi-choice test picked the correct response. In these two test, there was less than 10% of the students who could point out that the white smoke, coming out from the kettle is tiny water drops, while 70% of the students thought that it was water vapor. The evaluation results of open-ended written test indicated that more students' views, and examining the students' views carefully, the researchers found out that the keypoints to intermediate students' learning of these target concepts is that there should be more clarification of how water vapor exists in the air. Also in this study it was found that the format of the test has a great influence on the performance of the students' answers.
| Keywords: | Open-Ended Written Test; Evaporation; Condensation |
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