This paper proposes a new way to integrate history of science in science education to promote conceptual change by introducing the notion of historical microworld, which is a computer-based interactive learning environment respecting historic conceptions. In this definition, "interactive" means that the user can act upon the virtual environment by changing some parameters to see what ensues. "Environment respecting historic conceptions" means that the "world" has been programmed to respect the conceptions of past scientists or philosophers. Three historical microworlds in the field of mechanics are presented in this article: an Aristotelian microworld respecting Aristotle's conceptions about movement, a Buridanian microworld respecting the theory of impetus and, finally, a Newtonian microworld respecting Galileo's conceptions and Newton's laws of movement.