The experience of mathematical structure may be supported by representing mathematical knowledge graphically in the form of networks. In this paper, two special graphical representations of mathematical networks, mind maps and concept maps, are presented. Both knowledge maps are means to show ideas and concepts connected with a topic, in a well-structured form. Their special fitting as a pedagogical tool for mathematics education is pointed out, especially with regard to build structure. Possible uses of the presented knowledge maps together with their advantages and limits are discussed and classroom experiences collected from 9 teachers of different schools are presented. It turns out that knowledge maps, like mind maps and concept maps, may be efficient tools for building structure in mathematics.