In this article, the author presents three different tasks that can be used to assess students' understanding of the concept of length. Three important measurement concepts for students to understand are transitive reasoning, use of identical units, and iteration. In any teaching and learning process it is important to acknowledge students'…

The exponential function model of radioactive decay and the concept of a half-life are used in nuclear experiments that appear in introductory and intermediate laboratories. In our interactions with students, we have found that students at all levels have significant confusion about both the term exponential and what is meant by a half-life as…

Explores the difficulties students have in understanding the relationship between surface area and volume. Examines four cases where the ratio of surface area to volume varies, and makes recommendations for demonstrating each with models. (Contains 15 references.) (WRM)