Welcome to GeomLab

Note: The GeomLab application has recently been updated with a version that is properly signed with a certificate that should be accepted by most browsers. In addition, its appearance has changed to a single window in place of the separate editing and picture windows, and it is used in a slightly different way.

Even if you have used GeomLab before, please take a moment to look at the getting started page for instructions.

This web site will introduce you to some of the most important ideas in computer programming in an interactive, visual way through a guided activity. The activity is about a language for describing pictures. You will use a programming environment that lets you type an expression in the language, and shows you the picture that it describes.

At first, the pictures you will make will be simple combinations of stick figures: three men in a row, or one man supporting two smaller men. But gradually, the pictures will get more complicated, and soon we will be describing pictures like the one shown on the welcome page. That picture looks frighteningly complicated, but like all the pictures we will describe, it consists of a few basic tiles combined according to some fixed rules. Although the picture is complicated, it clearly has some kind of structure, and we will describe the structure in the form of a computer program that can generate it. Launch GeomLab Click on the Big Green Arrow to launch the GeomLab programming environment. You may have to accept a security certificate to allow the program to run on your computer; and it may be that the Java installation on your computer will be automatically upgraded before the program starts.