Cut out a number of circles from card stock, or paper glued to thin cardboard, like a cereal box.
We used a round lid for a guide.
Draw lines through the center of the circle to divide it into fourths, or eighths.
Color in the "pie" pieces in different colors. We used primary colors.
Stick a sharpened pencil through the center of the circle.
Spin the circle, and pencil, like a top. You might need to balance it between your fingers as it spins, to keep it from falling over, and you'll want to place a paper underneath, or you'll be drawing on your table.
Watch the colors as the top spins. The colors merge together.
It's a similar effect to what we saw with the thaumatropes we made a few months ago, except that it only suggests color to the brain. What I mean by this, is that each of the children in our house, saw the color differently. Using our disk that was half red, a quarter blue, and a quarter yellow, one child saw orange, one saw green, and one saw the colors underneath, with a glowing green over the top.
Scientists are still a little unsure as to what goes on between the brain and the eyes, that cause this optical illusion. It's the tip an interesting iceberg of study into neuroscience - but that's matter for another post.
It's great to be a homeschooler.