In this paper, we will first describe the instructional purposes and design of the Interactive Frog Dissection. We will discuss the importance of the web's HTML for development and for distribution and use. We will then describe the design of Net-Frog, and the ways that the heavily visited web site (over 62.000 separate visits were logged in its first eight months) is being used. Finally, we will consider how use of Net- Frog has encouraged use of the Internet.