Watch your solution change color as you mix chemicals with water. Then check molarity with the concentration meter. What are all the ways you can change the concentration of your solution? Switch solutes to compare different chemicals and find out how concentrated you can go before you hit saturation! Review teacher-submitted activities for ideas on embedding this interactive into lessons.

PHET Description:Make a whole rainbow by mixing red, green, and blue light. Change the wavelength of a monochromatic beam or filter white light. View the light as a solid beam, or see the individual photons.

Teacher Description: if you are a science teacher you are probably familiar with PhET Simulations. The website has many sims for things like matter, waves, and molecules that are help students visualize the abstract or very tiny. This sim is good is appropriate for teaching students how color filters work, and demonstrates that white or colorless light is made up of all colors.