Start a chain reaction, or introduce non-radioactive isotopes to prevent one. Control energy production in a nuclear reactor! (Previously part of the Nuclear Physics simulation - now there are separate Alpha Decay and Nuclear Fission sims.)

This video segment adapted from FRONTLINE looks at nuclear fission as an energy source that can be used to generate electricity.

This video segment produced for Teachers' Domain features a time-lapse video of clouds forming, changing, and moving across the sky.

This brief video segment produced for Teachers' Domain features time-lapse video of a sunrise and a sunset.

This video segment adapted from Shedding Light on Science illustrates how light changes speed, and thus direction, in a process known as refraction.

See how the equation form of Ohm's law relates to a simple circuit. Adjust the voltage and resistance, and see the current change according to Ohm's law. The sizes of the symbols in the equation change to match the circuit diagram.

See how the equation form of Ohm's law relates to a simple circuit. Adjust the voltage and resistance, and see the current change according to Ohm's law. The sizes of the symbols in the equation change to match the circuit diagram.

This video segment adapted from NOVA follows the clean-up effort after the 1989 Exxon Valdez oil spill off the coast of Alaska. Also featured is a marsh where an oil spill occurred 20 years earlier; analysis suggests that environmental damage may last for decades.

Explore an active area of research in optical physics: producing designer pulse shapes to achieve specific purposes, such as breaking apart a molecule. Carefully create the perfect shaped pulse to break apart a molecule by individually manipulating the colors of light that make up a pulse.

Did you ever imagine that you can use light to move a microscopic plastic bead? Explore the forces on the bead or slow time to see the interaction with the laser's electric field. Use the optical tweezers to manipulate a single strand of DNA and explore the physics of tiny molecular motors. Can you get the DNA completely straight or stop the molecular motor?

Did you ever imagine that you can use light to move a microscopic plastic bead? Explore the forces on the bead or slow time to see the interaction with the laser's electric field. Use the optical tweezers to manipulate a single strand of DNA and explore the physics of tiny molecular motors. Can you get the DNA completely straight or stop the molecular motor?

This activity helps students develop a sense of the relative size of quantities in time, length and mass. Learners rank their estimates of given measures in order from least to greatest and justify their decisions. The Teachers' Notes page includes suggestions for implementation, discussion questions, ideas for extension and support, printable cards (pdf), and a link to a related problem, "In Order" (cataloged separately). The solutions page shows that students used standard units of measure to make their comparisons.

This video segment adapted from NOVA explains the origin of the elements and how scientists use unique element profiles to identify supernova types.

This video segment adapted from NOVA follows the Apollo 15 astronauts as they collect samples of ancient rock from the Moon's crust, whose discovery helps lead to a radical new theory about the Moon's origin.

In this interactive activity from ChemThink, examine the basic properties of matter at an atomic level and consider how various atoms affect the way a substance behaves.

Play with one or two pendulums and discover how the period of a simple pendulum depends on the length of the string, the mass of the pendulum bob, and the amplitude of the swing. It's easy to measure the period using the photogate timer. You can vary friction and the strength of gravity. Use the pendulum to find the value of g on planet X. Notice the anharmonic behavior at large amplitude.

The People's Physics Book v3 is intended to be used as one small part of a multifaceted strategy to teach physics conceptually and mathematically

This interactive periodic table developed for Teachers' Domain provides detailed information about the chemical properties of elements and illustrates the electron configurations that determine those characteristics.

See how light knocks electrons off a metal target, and recreate the experiment that spawned the field of quantum mechanics.