In a large bowl, combine ¼ cup of chia seeds, 2 cups of water, and a few drops of food coloring.
Stir well to evenly distribute the seeds.
Cover the bowl and pop it in the fridge overnight (or at least 4-6 hours).
Repeat for as many colors you would like.
Stir the mixture and spoon into a sensory bin or a shallow tray.
Let the messy fun begin!