Pour water into blender.
Add 5-10 drops of food coloring and run blender for a few seconds to combine.
Add dish soap to blender. Turn on blender and run on high speed for 1-3 minutes, until mixture is nice and foamy.
Repeat previous steps to create as many colors as you like. Then, place the soap foam in a large bin, bathtub or water table and let your child play!
