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.

‪Balancing Chemical Equations‬

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 …

Design and explore your own solar system with interactive simulations, observing gravitational forces and celestial body orbits.

‪States of Matter: Basics‬