Make copies of a picture of a rainbow from a coloring book. Give each child a piece of paper featuring the outline of the rainbow; provide kindergartners with red, orange, yellow, green, blue and purple crayons. Teach children that these are the colors which make up the rainbow, and show them how to decorate their picture, arranging the hues in the correct order. Explain that the rainbow contains three primary colors: red, yellow, and blue. Teach the children that the shades between the primary colors are the result of those colors mixing. For example, red and yellow combine to make orange; hence, its place as the second color in the rainbow between its parent shades.
Let children participate in mixing primary colors so they will learn about the role that primary colors play in creating secondary colors. Give each child a paper plate, and place many shades of finger paint on the table. Cover the table and carpet with newspapers. Ask the children to combine two of the primary colors from the rainbow. For example, they can place a dab of blue and a dab of red on their paper plates. Tell the children to swirl the paint together using their fingers, which results in purple paint. Repeat with other combinations of primary colors. This interactive activity will help children understand the way that primary colors of the rainbow combine to create secondary hues.
Bring a variety of colored scarves to school, including the primary colors and the colors they create when combined. Give each child a scarf. If kindergartners have preferences and favorite colors, let them choose their own scarves. Bring one scarf per student and let more than one student hold scarves of the same color. Tell the class they will be performing a skit involving the primary colors. Ask children who are holding scarves of different primary colors to stand on opposite sides of the room. Tell two primary colors to walk toward each other and explain that when they meet in the middle of the room, they combine to create another color. Ask children holding scarves of a corresponding secondary color to run to the center of the room when they see their primary colors combining. Repeat the activity until all students have memorized the different combination options regarding primary colors.
Bring squares of transparent plastic to class that are tinted each color of the rainbow. Assemble kindergartners in front of the overhead projector. Use the pieces of colored plastic to demonstrate the way primary colors combine to create secondary. For example, place a piece of blue plastic on the overhead projector and place a yellow piece on top of it. Kindergartners will be amazed at the resulting green light. Ask for student volunteers to create purple and orange by combining primary colors. Repeat the activity until all students have had the opportunity to merge colors to create different shades and everyone understand the combinations that are possible.