Free science and math simulations for teaching STEM topics, including physics, chemistry, biology, and math, from University of Colorado Boulder

By converting our sims to HTML5, we make them seamlessly available across platforms and devices. Whether you have laptops, iPads, chromebooks, or BYOD, your favorite PhET sims …

Build an atom out of protons, neutrons, and electrons, and see how the element, charge, and mass change. Then play a game to test your ideas!

‪Natural Selection‬

‪States of Matter‬

‪Gravity and Orbits‬

Explore diffusion with interactive simulations, adjusting variables like concentration and temperature to observe their effects on the process.

‪States of Matter: Basics‬

Studio About Studio Customizable Sims Start a Free Trial Purchase a License Teaching Activities Contribute an Activity Activity Contribution Guidelines Virtual Workshops Tips for Using PhET …

This is an interactive sim. It changes as you play with it.