The study of problem solving and learning with multiple representations is not only of scientific interest. Besides providing insight into complex reasoning and problem solving that characterizes much human performance, it is of direct relevance as a technology for underpinning applications of the new multimedia technology. Educational applications of multimedia technology open a wide range of representational formats in which knowledge can be presented to learners. Without understanding how learners use knowledge in different representations for problem solving and learning it will not be possible to make optimal use of this new technology. The chapters in this book give an overview of our understanding of the role of multiple representations and show that the effects can be subtle and require a good understanding of the task or domain, the goal of learning and human cognition. Split into 3 parts, part 1 addresses problem solving with knowledge that is represented in multiple representations and the associated issue of skill acquisition from solving multiple representaions.