How can science teachers support students in developing an appropriate declarative knowledge base for solving problems? This article focuses on the question whether the development of students' memory of scientific propositions is better served by writing propositions down on paper or by making drawings of propositions either by silent or muttering rehearsal. By means of a memorisation experiment with eighth- and ninth-grade students, we answer this question. In this experiment, students received instruction to memorise nine science propositions and to reproduce them afterwards. To support memorisation students were randomly assigned either to a group that received instruction to write each proposition on paper or to a group that received instruction to make a drawing about the content of the proposition. In addition, half of the students in both groups received instruction to mutter and the other half of them received instruction to write or draw in silence. The main conclusion from the experiment is that after four weeks students who had made a drawing remembered significantly more propositions than those who had memorised the propositions by writing them down. Our research further revealed that it did not matter whether students muttered or memorised silently.