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 are always right …

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

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

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 …

‪Forces and Motion: Basics‬

‪Gravity and Orbits‬

Explore natural selection through interactive simulations, observing how traits influence survival in changing environments.