Make a batch of play dough and leave it white. Form several balls of the dough and place a drop or two of food coloring in the middle of the ball. Give the dough to the children to play with. They will be very surprised when the dough starts turning colors! They can also knead together two different balls to see what colors they can make.
I have a large plastic jug (it was a pickle jar I got from a local deli). I fill it with water and let the water sit till calm, then I drip drops of food coloring into the water one at a time. My 3-year-olds can watch the color drift in the water for 10-15 minutes. We add colors as they request and occasionally add an Alka-Seltzer tablet for fun.
When I do colors I use white cake icing and teach them to mix colors. I use a couple drops of food coloring and add it to the frosting such as one drop of red and one drop of blue have them mix it together and they learn to make purple plus they get to eat their “science project”.
Fill three plastic squeeze bottles with yellow, blue and red water. Give a white ice cube tray to the child and fill the 1st three “holes” with red, yellow and blue water. Give the child an eye dropper (or medicine dropper) to mix the colors in the empty “holes”. It’s amazing how many shades there are of the different colors.
Read Little Blue Little Yellow by Leo Lionni. Follow up with great art/science activity ~ Add blue food color to small container of bubbles and yellow to another. Let the children blow bubbles. As the bubbles pop onto paper they make blue or yellow circles. Children will discover green “popping” up whenever the blue and yellow mix.
Here is a recipe for making rainbow stew! Get a small pot and mix about 1 cup of cornstarch with some water. Heat the mixture up until very thick. Remove the “stew” from the heat and place in a sturdy Ziploc bag. Add several drops of different colored food coloring and duct tape the top to help prevent inquisitive fingers. Place on science table and allow children to manipulate the stew and observe the changes in color.