Soap & Pepper Science Experiment for Kids | Learn About Surface Tension

What You'll Need

• Transparent bowl (e.g., a glass baking dish or clear plate) • Water • Ground black pepper (or other fine spice like oregano) • Liquid soap (dish soap works best) • Small dish or container for soap • (Optional) The printed "Soap & Pepper Experiment" sheet

Getting Started

• If using the printed sheet, place it on a flat surface. • Carefully place the transparent bowl on top of the printed sheet (if using) or directly on a table. • Pour enough water into the bowl to cover the bottom with a shallow layer (about 1/2 inch deep). • Sprinkle a generous amount of ground black pepper evenly across the surface of the water. Make sure it's floating and not sinking. • Pour a small amount of liquid soap into a separate small dish or container.

How to Do This Activity

• First, have your child gently dip just the tip of their clean finger into the center of the pepper-covered water. • Observe what happens. (Likely, nothing much will happen, or the pepper might stick to their finger). • Now, have your child dip the tip of the same finger into the small dish of liquid soap, getting a tiny bit of soap on their fingertip. • Immediately and gently dip the soapy fingertip into the very center of the pepper-covered water again. • Watch in amazement as the pepper dramatically scatters and rushes to the edges of the bowl, away from the soapy finger!

Tips for Parents

• Before starting, ask your child what they think might happen when they dip their finger in the water, and then with soap. • Discuss the "How?" explanation provided on the printable: Water molecules like to stick together (surface tension), which keeps the light pepper afloat. Soap breaks this tension, causing the water molecules to spread out quickly, taking the pepper with them. • Connect this experiment to real-life: Explain that soap works similarly on germs and dirt on our hands, pushing them away so they can be rinsed off. This reinforces the importance of handwashing! • Encourage your child to describe what they see and how they feel about the "magic" of the soap.

Ways to Extend

• Try the experiment again with different liquids (e.g., milk instead of water, though results may vary). • Experiment with different fine spices or glitter instead of pepper to see if they react similarly. • Discuss other ways soap helps us clean things around the house. • For older children, research more about surface tension and other scientific properties of water.