# Turtles Why do we call these objects "turtles"? There is a long tradition. It started in the 1950s when a scientist named Grey Walter built a small mechanical robot. Walter programmed the robot to act like a real creature: for example, when the robot was low on energy, it began to look for "food" (a recharger). Walter called his robot a turtle because it had a turtle-like "shell" on top to protect its electronics. In the 1960s, Seymour Papert and his colleagues at MIT built a similar robot turtle. But they wanted children, not scientists, to program the turtle. So they created a new programming language called Logo that made it easy for children to program the turtle's motion. Logo was intended to provide children with a new way of "playing" with (and learning) mathematical ideas. Later, as computers (and displays) became less expensive, the Logo turtle moved onto the computer screen. Millions of school children have created graphics and animations by giving Logo commands to turtles on the computer screen. This active essay uses a version of Logo called MicroWorlds which has a plug-in for use on the World Wide Web. There is another version of Logo, called LEGO/Logo, that brings the turtle back to the physical world. With LEGO/Logo, children can build machines and creatures out of LEGO materials, then write Logo programs to control their creations. Children have used LEGO/Logo to create programmable amusement-park rides, moving sculptures, automated houses -- and, yes, LEGO turtles. Go back to the active essay.