In mathematics education, physical manipulatives such as algebra tiles, pattern blocks, and two-colour counters are commonly used to provide concrete models of abstract concepts. With these traditional manipulatives, people can communicate with the tools only in one another's presence. This limitation poses difficulties concerning assessment and accessibility for teacher educators. In this article, I present a possible solution through the use of savable-state virtual manipulatives, including examples from my own classes. Through example work centring on the theme of "zero pairs" in algebra, I will discuss how such an applet can be used as a tool for creating representational models, bridging the gap between the concrete and symbolic representations. (Contains 10 figures.)