Improving the Teaching of Estimation through an Analysis of Textbook Activities

Measurement involves actual measuring or estimating to generate a quantitative understanding of a phenomenon. Estimation in particular refers to the process of obtaining measurements without a measuring tool. This paper aims to investigate didactical implications for estimation by analyzing the estimation activities of textbooks. To this end, we focused on estimation activities in elementary school mathematics textbooks from the seventh to the 2015 revised national curriculum, analyzing them based on activity quantity, estimation type, and estimation strategy. As regards length, the estimation activities were presented appropriately in terms of quantity, type, and strategy. However, other attributes were insufficient in quantity while some activities showed biases and limitations with few estimation strategies to use in a variety of contexts. Based on these results, we propose the inclusion of achievement standards for time, area, and volume and argue that the textbook should address various types of and strategies for estimation activities.