This video segment adapted from NOVA features a variety of scientific perspectives on the age old question, "Are we alone in the universe?" Animations make vivid the improbability that we could intercept a radio wave signaling extra terrestrial intelligence.

Students will complete this survey that determines their personal and household contributions to atmospheric Carbon dioxide by using information about their previous year's consumption. They will understand that Carbon dioxide is a greenhouse gas produced by the combustion of fossil fuels, and that its production can be minimized by taking personal steps to conserve.

In this video, David explains how an atom can absorb and emit photons with particular values of energy and how to determine the allowed values.

The impact of natural disasters is made vivid in this video segment adapted from NOVA. A small town in Iceland, prepared for recurrent avalanches, is devastated when one takes a new and damaging path.

This trick from Exploratorium physicist Paul Doherty lets you add together the bounces of two balls and send one ball flying. When we tried this trick on the Exploratorium's exhibit floor, we gathered a crowd of visitors who wanted to know what we were doing. We explained that we were engaged in serious scientific experimentation related to energy transfer. Some of them may have believed us. If you'd like to go into the physical calculations of this phenomenam, see the related resource "Bouncing Balls" - it's the same activity but with the math explained.

This video segment describes how the Australopithecus afarensis skeleton known as Lucy could have been fossilized. Footage courtesy of NOVA: "In Search of Human Origins."

Demonstrate the Bernoulli Principle using simple materials on a small or large scale. This resource includes two activities that allow learners to experience the Bernoulli Principle, in which an object is suspended in air by blowing down on it. Use this activity to explain how atomizers work and why windows are sometimes sucked out of their frames as two trains rush past each other.

This is the first of two videos where Sal derives Bernoulli's equation. Created by Sal Khan.

This is the second of two videos where Sal derives Bernoulli's equation. In the second half of the video Sal also begins an example problem where liquid exits a hole in a container. Created by Sal Khan.

This ZOOM video segment shows how to create a self-contained environment and explores evaporation, condensation, and precipitation.

The purpose of this resource is to quantitatively evaluate the accuracy of a classification system. Students sort birds into three possible classes based on each bird's beak: carnivores, herbivores, and omnivores. Students compare their answers with a given set of validation data.

Calculating electron energy for levels n=1 to 3. Drawing a shell model diagram and an energy diagram for hydrogen, and then using the diagrams to calculate the energy required to excite an electron between different energy levels. Created by Jay.

Using classical physics to calculate the energy of electrons in Bohr model. Solving for energy of ground state and more generally for level n. Created by Jay

Using equation for Bohr model radii to draw shell model for n=1 to 3, and calculating the velocity of a ground state electron. Created by Jay

Using classical physics and vectors, plus assumption that angular momentum of electron is quantized, to derive the equation for Bohr model radii. Created by Jay.

A couple of problems involving Archimedes' principle and buoyant forces. Created by Sal Khan.

CK-12 Physical Science Concepts covers the study of physical science for middle school students. The 5 chapters provide an introduction to physical science, matter, states of matter, chemical interactions and bonds, chemical reactions, motion and forces, and the types and characteristics of energy.

In this demonstration, cook a cake using the heat produced when the cake batter conducts an electric current. Because of safety concerns, this activity should be conducted as a demonstration only and learners should be kept at a safe distance.

Calculating the dot and cross products when vectors are presented in their x, y, and z (or i, j, and k) components. Created by Sal Khan.