Mosaics are a great way to teach little ones to look for color. You'll need some large (12-by-12 inch) pieces of white construction paper and a black marker. Draw some large but simple designs on the paper, such as a sun, a house or a car. If you're approaching holidays, you could draw a pumpkin or a snowman. Provide each child with one of your drawings and several colorful pieces of paper from old magazines.
Have the kids look for pictures with the colors they'll need to fill in their pictures. For instance, for a sun, kids will want to look for lots of orange and yellow pieces. They can tear or cut those pieces out, then tear them into small (1-by-1-inch) squares. Once they've gathered the pieces they want, have them glue them onto their image. You can use these to decorate your classroom, or you could laminate them for the kids to use at home as place mats.
Little ones may be delighted to see different colors swirl together in this activity. You'll need an aluminum pie pan and some white paper. Cut the white paper to fit the inside of the pie plate, then tape it down to the middle of the plate. Put some tempera paints into the different cups of an empty, clean egg carton, then add a marble to each cup filled with paint. With tongs, pull a 2 to 3 marbles out, then drop them into the pie pan. Have kids rock the pie pan back and forth and move it around so that the colors swirl all over the paper. When you see colors mixing together to form new ones, point this out to the kids. You can also have them guess what colors will result from mixing colors.
While there are many colors in the world around us, there are only three primary colors. The primary colors red, yellow and blue make up all of the colors we see. In 1966, Sir Isaac Newton created the color wheel. You can have your students replicate this in a kinesthetic way. Because this project takes a while to put together, it might be good to add a hand print one at a time as you discuss the colors with your students; they may enjoy having a big "project" they're working on.
On a large piece of white construction paper, have your students do a yellow, red and blue hand print either with paint or by tracing their hands on construction paper, cutting it out and gluing it to their paper. They'll need to do it in a triangle, as with any color wheel. They can then do hand prints for the secondary colors as you cover them, followed by tertiary colors if you discuss them. Alternatively, you could turn this into a class project by having students take turns doing one hand print onto a large piece of white butcher paper and displaying their design on a bulletin board.