Awesome Osmosis

Ideal for Preschool/Pre-K , School-Age

Paper towels from a glass of water bent into one orange water glass and one blue water glass in an osmosis experiment | Bright Horizons | STEM Activities

This activity promotes development and learning by encouraging children to demonstrate an understanding of cause-and-effect as they explore the concept of osmosis.

Materials Needed:

  • 3 clear cups
  • Yellow and blue food coloring
  • Paper towels

Participants: This activity is intended for adult/child interaction.


  • Step 1: Roll two long pieces of the paper toweling into tightly coiled lengths.
  • Step 2: Fill the cups with water. Add yellow food coloring to one cup and blue food coloring to another. Do not add food coloring to the third cup.
  • Step 3: Place the end of one paper towel length in the blue water and the other end in the plain water. Place one end of the other paper towel length in the yellow water and the other end in the plain water. Watch as color from both cups moves into the plain water creating a new color.
  • Step 4: Ask your child why they think the color moved into the plain water. What questions does your child have? Does hot water work differently than cold water, for example, or do some brands of paper towels work better than others and why.

Extensions: Do a few more experiments based on your child’s wonderings.

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