The study curriculum that will be implemented in 2002 is slimmer than that of the 1989 curriculum. Many people, who are anxious about the decline of students\u27 basic knowledge, have discussed the problems associated with the slimmer version. However, since basic data on scholastic ability in elementary and lower secondary schools are limited, this argumentation becomes almost abstract. In this study, we have therefore examined students\u27 understanding of heat transfer comparing the year 1990 students to the year 2000 students for the concept of heat transfer and representation of heat. In order to avoid any controversy, the test was identical to that used ten years ago. The findings of the present study are as follows: 1. Fourth grade students who studied the concept of heat transfer, using a metal plate and inclined metal bar, have a level of understanding which is lower than students of the year 1990. This is because their curriculum did not include the cause of heat transfer. 2. Understanding of the phenomenon of convection is equal between unlearned third grade students and a learned group of students. 3. On the understanding of radiation, the students\u27 understanding of the year 2000 is lower than the students of 1990. 4. Third and fourth grade students think that a material becomes heavy if is warmed, and it becomes lighter if the material is cooled. Their reasoning is influenced by temperature change and cubic shrink proofing. 5. Elementary school students think that frozen material is heavier than unfrozen material. Ninth grade students realize that weight does not change even if the material freezes, however, only 50% understand that. 6. They make up their concepts about the relationship between weight and temperature changes based on their daily life experience, before they acquire a scientific conception about it. Therefore, even if students study the law of constancy of mass in the seventh grade, it is difficult to modify their misconceptions to a scientific conception. 7. This research revealed that the year 2000 students understanding and knowledge of the concepts of the heat transfer was lower than the 1990 students.国立情報学研究所『研究紀要公開支援事業』により電子化
