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

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!

Explore the states of matter with interactive simulations that show how molecules form solids, liquids, and gases.

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 at your fingertips.Become part of our mission today, and transform the learning experiences of students everywhere!

Build and test circuits with batteries, resistors, light bulbs, and switches. Learn about series and parallel circuits, Ohm's law, and conductors and insulators.

Experiment with an electronics kit! Build circuits with batteries, resistors, ideal and non-Ohmic light bulbs, fuses, and switches. Determine if everyday objects are conductors or insulators, and take measurements with an ammeter and voltmeter. View the circuit as a schematic diagram, or switch to a lifelike view.

Heat, cool and compress atoms and molecules and watch as they change between solid, liquid and gas phases.

Play with objects on a teeter totter to learn about balance. Test what you've learned by trying the Balance Challenge game.

Explore gravity and orbits with interactive simulations.

Explore energy conservation with a virtual skater in different skate parks and see energy graphs.