This article explores the relationship between abstract and concrete as categories of knowledge and Wilensky's (1991) theory that all ideas are abstract until they become concrete. Dewey (1910/1997) made a similar claim by suggesting that ideas are initially beyond our comprehension until they have become consolidated. This article documents the evolving mental models of 11- and 12-year-old children as they designed and made explanatory animations for the sake of their own learning. The conclusion from this research is that transferring ideas from thought to word, word to image, or transmediation of any kind, is a semiotic tool for cross-modal cognition.