Education has a long tradition in the use of illustrations. The aims of the illustrations are to make it easier and to clarify for the students. But is that really the case? The topic of this study is to generate knowledge about how children make use of illustrations in mathematical textbooks in primary school. This study focuses Swedish primary school in year one (7 years old) where video observations from twelve students were made. The empirical material was analyzed using affordances (Gibson, 1986) and subtraction situation (Fuson, 1992). The survey was conducted in accordance with the Swedish Research Council's ethical principles in the humanities and social sciences, which have four main demands: according to information, consent, confidentiality and utilization.The analysis showed that the students sometimes discover the aimed subtraction situation and/ or affordance and sometimes not. This affects how students handle the mathematical operations. A conclusion of this was that students have to discover the aimed subtraction situation as well as the aimed affordance to be able to handle a mathematical operation in the textbook in a desirable way. The result also showed a number of variables that effected how the students handled the illustrations. A conclusion of this was that the teacher plays an important role when students work with their textbooks. We live in a visual world and the ability to read illustrations are today of great importance. What is more, the mathematics education is a textbook controlled subject. Little has been written about how students make use of illustrations in mathematics book, especially concerning younger children. This is therefore of great importance.