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 …

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

Explore how organisms with different traits survive various selection agents within the environment.

Build your own system of heavenly bodies and watch the gravitational ballet. With this orbit simulator, you can set initial positions, velocities, and masses of 2, 3, or 4 bodies, and then see them orbit each …

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!

Founded in 2002 by Nobel Laureate Carl Wieman, the PhET Interactive Simulations project at the University of Colorado Boulder creates free interactive math and science simulations. PhET sims are …

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

‪States of Matter‬

Explore gravitational force and its effects on objects in an interactive simulation by adjusting mass, distance, and size parameters.