Understanding primary children’s thinking and misconceptions in decimal numbers

In Hong Kong, most of the primary school teachers are proud of their students in doing the four operations of decimal numbers. Inspecting a mathematics textbook might give the impression that, in order to be competent with decimal numbers, all that students need to do is remembering few rules for placing the decimal point, and otherwise perform operations with decimal numbers as if they were whole numbers. It seems to teachers and parents that primary students are able to line up decimal points and count decimal places. However, when asking a student to compare 4.8 and 4.75, he/she will choose 4.75 as the larger number because 75 is bigger that 8! In fact, the basic concepts of decimal number such as the place value and its relation with fraction are discussed at the early stage of learning decimals. However, the discussion is always too simplified and students do not understand thoroughly the underlying concept of decimal numbers but are pushed to learn the four operations of decimal numbers. Thus, students’ computational skills on four operations of decimal numbers are merely rote learning and devoid of any meaning. With this reason, the research aimed at developing a tool and using it to uncover students’ thinking and misconception on decimals. The significance of this research is to inform our pre-service student teachers and in-service teachers the general misconceptions of teaching and learning decimals, so that the focus and framework of teaching decimals could be restructured regarding students’ learning difficulties which were revealed in this research. Copyright © 2009 The Hong Kong Institute of Education.