Elementary Science:
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Exploring Surface Tension with Milk, Food Coloring, and Soap

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Grade Level: First Grade   

Book: Physical Science  Unit: Matter  Module: States of Matter


In this experiment, students will be introduced to surface tension and density through a colorful presentation.

Research Question:

What properties does surface tension itself affect?

Surface Tension allows liquids to resist an external force. This property allows some objects that are denser than water to actually float. Surface tension results from the greater attraction of water molecules to each other that to air.


  • Food coloring in colors of your choice
  • Milk
  • Dishwashing liquid
  • A large dish with raised sides

Experimental Procedure:

  • In a pretty deep dish, add about ½- 1 inch of milk.
  • Put a few drops of food coloring on the surface of the milk. The colors, amount, and arrangement can be however you like.
  • Put 2 drops of dishwashing liquid inside. 
  • Observe what happens to the surface of the milk.

Related Lesson:

States of Matter – Sillybulls


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