How do strong and weak acids differ? Use lab tools on your computer to find out! Dip the paper or the probe into solution to measure the pH, or put in the electrodes to measure the conductivity. Then see how concentration and strength affect pH. Can a weak acid solution have the same pH as a strong acid solution?

Watch alpha particles escape from a polonium nucleus, causing radioactive alpha decay. See how random decay times relate to the half life.

Watch alpha particles escape from a polonium nucleus, causing radioactive alpha decay. See how random decay times relate to the half life.

Create your own shapes using colorful blocks and explore the relationship between perimeter and area. Compare the area and perimeter of two shapes side-by-side. Challenge yourself in the game screen to build shapes or find the area of funky figures. Try to collect lots of stars!

This simulation gives students the opportunity to explore both area and perimeter of 2-dimensional shapes. Students can explore by creating shapes and having the sim calculate the area and perimeter. They can also play a game where the goal is to create a shape with a specified area or area and perimeter, or to calculate the area and/or perimeter of a given shape.

Build rectangles of various sizes and relate multiplication to area. Discover new strategies for multiplying algebraic expressions. Use the game screen to test your multiplication and factoring skills!

Build rectangles of various sizes and relate multiplication to area. Partition a rectangle into two areas to discover the distributive property.

Build rectangles of various sizes and relate multiplication to area. Discover new strategies for multiplying large numbers. Use the game screen to test your problem solving strategies!

Remember your multiplication tables? ... me neither. Brush up on your multiplication, division, and factoring skills with this exciting game. No calculators allowed! The students will be given mutiplication and division problems which they must answer. They also have the option of being given a number then stating the factors of how that number was attained using either multiplication or division.

Remember your multiplication tables? ... me neither. Brush up on your multiplication, division, and factoring skills with this exciting game. No calculators allowed!

Brush up on your multiplication, division, and factoring skills with this interactive multiplication chart. Three levels and timed or untimed options are available.

Explore the interactions between various combinations of two atoms. Turn on the force arrows to see either the total force acting on the atoms or the individual attractive and repulsive forces. Try the "Adjustable Attraction" atom to see how changing the parameters affects the interaction.

Explore the interactions between various combinations of two atoms. Turn on the force arrows to see either the total force acting on the atoms or the individual attractive and repulsive forces. Try the "Adjustable Attraction" atom to see how changing the parameters affects the interaction.

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

How do you know if a chemical equation is balanced? What can you change to balance an equation? Play a game to test your ideas!

Experiment with a helium balloon, a hot air balloon, or a rigid sphere filled with different gases. Discover what makes some balloons float and others sink.

Students explore static electricity by rubbing a simulated balloon on a sweater. As they view the charges in the sweater, balloon, and adjacent wall, they gain an understanding of charge transfer. This item is part of a larger collection of simulations developed by the Physics Education Technology project (PhET). The simulations are animated, interactive, and game-like environments.

Why does a balloon stick to your sweater? Rub a balloon on a sweater, then let go of the balloon and it flies over and sticks to the sweater. View the charges in the sweater, balloons, and the wall.

Explore the origin of energy bands in crystals of atoms. The structure of these bands determines how materials conduct electricity.

Explore the origin of energy bands in crystals of atoms. The structure of these bands determines how materials conduct electricity.

Look inside a resistor to see how it works. Increase the battery voltage to make more electrons flow though the resistor. Increase the resistance to block the flow of electrons. Watch the current and resistor temperature change.

Look inside a battery to see how it works. Select the battery voltage and little stick figures move charges from one end of the battery to the other. A voltmeter tells you the resulting battery voltage.

Look inside a battery to see how it works. Select the battery voltage and little stick figures move charges from one end of the battery to the other. A voltmeter tells you the resulting battery voltage.

The PhET project at the University of Colorado creates "fun, interactive, research-based simulations of physical phenomena." This particular one deals with Beer's Law. "The thicker the glass, the darker the brew, the less the light that passes through." Make colorful concentrated and dilute solutions and explore how much light they absorb and transmit using a virtual spectrophotometer! The simulation is also paired with a teachers' guide and related resources from PhET. The simulation is also available in multiple languages.

Explore bending of light between two media with different indices of refraction. See how changing from air to water to glass changes the bending angle. Play with prisms of different shapes and make rainbows.

Watch beta decay occur for a collection of nuclei or for an individual nucleus.

Watch beta decay occur for a collection of nuclei or for an individual nucleus.

How does the blackbody spectrum of the sun compare to visible light? Learn about the blackbody spectrum of the sun, a light bulb, an oven, and the earth. Adjust the temperature to see the wavelength and intensity of the spectrum change. View the color of the peak of the spectral curve.

Starting from atoms, see how many molecules you can build. Collect your molecules and see them in 3D!

Build fractions from shapes and numbers to earn stars in this fractions game or explore in the Fractions Lab. Challenge yourself on any level you like. Try to collect lots of stars!

Build fractions from shapes and numbers to earn stars in this fractions game or explore in the Fractions Lab. Challenge yourself on any level you like. Try to collect lots of stars!

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!

When will objects float and when will they sink? Learn how buoyancy works with blocks. Arrows show the applied forces, and you can modify the properties of the blocks and the fluid.

When will objects float and when will they sink? Learn how buoyancy works with blocks. Arrows show the applied forces, and you can modify the properties of the blocks and the fluid.

Explore how a capacitor works! Change the size of the plates and add a dielectric to see how it affects capacitance. Change the voltage and see charges built up on the plates. Shows the electric field in the capacitor. Measure voltage and electric field.

Move point charges around on the playing field and then view the electric field, voltages, equipotential lines, and more. It's colorful, it's dynamic, it's free.

Move point charges around on the playing field and then view the electric field, voltages, equipotential lines, and more. It's colorful, it's dynamic, it's free.

This new version of the CCK adds capacitors, inductors and AC voltage sources to your toolbox! Now you can graph the current and voltage as a function of time.

Build circuits with capacitors, inductors, resistors and AC or DC voltage sources, and inspect them using lab instruments such as voltmeters and ammeters.

An electronics kit in your computer! Build circuits with resistors, light bulbs, batteries, and switches. Take measurements with the realistic ammeter and voltmeter. View the circuit as a schematic diagram, or switch to a life-like view.