Dye one cup for each color in the rainbow by stirring a few drops of food coloring into 1 cup dry white rice. Pour each cup of colored rice into individual translucent gift bags and sew them shut. Arrange the bags by color in a row on the table, and encourage the toddlers to touch and manipulate them. Paint a rainbow progression of squares at the bottom of the sensory table so the toddlers have a correct reference when positioning the bags of rice.
Cut six 4-inch-wide arches of sandpaper so they make a rainbow when arranged correctly. Paint an example of a arching rainbow at the bottom of the table. Use grey or pale sandpaper, and paint each strip a different color in the rainbow. Spread the sandpaper arches around the table and allow children to experiment with the position and order while gently touching the textured material.
Create a waving rainbow ribbon using all the toddlers in the group. Give each child one 2-foot long strip of ribbon in a single color. For example, one child would have a red ribbon, another child an orange ribbon, and so on. Divide the children into groups of six, and arrange them one at a time by color. Announce the addition of each child and his ribbon to the rainbow to reinforce the correct sequence of colors of the rainbow. Ask them to wave their ribbons high once they join the group. When complete, the toddlers will see a room full of friends forming groups of waving rainbow ribbons.