To Do and Notice:

1. Click on the "change background color" icon at the right to set a new background color.

2. Now try to make the circle match the background. Adjust the balance of the three colors of light: red,blue, and green by clicking the + or - buttons for each color.

When the color of the circle matches the color of the background, the circle will disappear.

3. To check your answer against the exact color mix of the background, click on the "check color levels" icon. Small arrows will appear next to each color column, indicating the amount of each color used.

4.Try matching another color by clicking the "change background color" icon on the bottom right. Notice that the color of the center circle may appear to change when you change the background.

What's Going On?

You can match millions of different background colors by mixing three colors of light: red, blue, and green.

You'll notice that mixing colored light is very different from mixing colored pigments or paint. It may seem very tricky at first. Pigment colors get darker as they combine. When you add more colors of paint, the pigments absorb more and more of the light shining on the paint.

But when you add more colored light, the color of the circle gets lighter. When you add all the colors of light together, you get white light.

When you changed the background color, the color of the circle didn't change. But it probably looked different to you because of the contrast between it and the background color. A medium color will look dark against a lighter background, and light against a darker background.