The primary school teachers' understanding on the derived units in arithmetic

Abstract

In the elementary school teaching guide for the Japanese course of study, the units on population density and speed are indicated as examples of derived units in mathematics. However, derived units other than area or volume are not taught in elementary school lessons. The study investigated this with the aim of obtaining suggestions on instruction methods concerning “size per unit quantity” and “speed,” based on the units. Primary school teachers participated in this study and their understanding of the derived units was examined. Three solutions to each problem for (the number in a group) × (the number of groups) ＝ (the total number) that were presented to the participants, who were asked to write down the unit of each value in the solution. At the same time, the participants’ profiles were asked. Results showed that the participants understood the derived units of speed, such as “km/h” regardless of their years of experience as a teacher, and their math or science ability. However, their understanding about the unit of the quantity calculated by multiplication or division for two types of quantities without the derived units of speed was not enough.