The number line as a representation at subtraction- A qualitativ content analysis of textbooks in mathematic.

The number line as a representation at subtraction- A qualitative content analysis of textbooks in mathematic. Number sense has a prominent role in mathematics. It is an ability seen as the basis for the student´s continued development in mathematics. In my work as a teacher it´s a topic that is often discussed in the context of students’ mathematical difficulties. That´s why I found it important to study further. According to two different reports about how the teaching of mathematics in Swedish schools is conducted a large part is devoted to individual work in the book. Taking that into account it´s important to review what it is students face when they work in their textbooks in mathematics. This study is a review of two different base learning materials in mathematics for grades 1-3. The purpose of the review is to describe how mathematics learning materials use the number line in the context of explaining subtraction and to reflect the possibilities for the students to develop number sense. The method used in the study is a qualitative content analysis. The theory behind the study is constructivism together with McIntosh, Reys and Reys (1992) framework about number sense and Thompson´s (1999) way to explain different strategies for mental arithmetic in subtraction. The result of the study shows that the textbooks mostly use the number line within the number range 0-20. The number line is linear and up to twenty it often starts with 0. If it´s used over twenty it only shows the number area the terms of the task are within. The number line mostly shows counting instead of calculating. When the numbers to count with get bigger, algorithms are introduced. One of the reasons for that may be the difficulty to show the size of the amounts with the number line