Thursday, March 10, 2016

Home Learning: Water #4

We continued to explore water's surface tension. I had a few little experiments to try. 

First, we put some ground pepper on a cup of water.  The pepper mostly floated.  We used a toothpick dipped in liquid detergent to touch the water.  As soon as it touched the water surface, the pepper fell down to the bottom of the cup. To the kids it looked like magic.  But after talking about it, they remembered that soap weakens the surface tension. Without the surface tension, water couldn't hold the pepper on the top.  Therefore, the pepper sank. 

The preparation for the second experiment was a lot of fun.  They cut a piece of paper with the image of a water walking insect. They also filled up a container with 7 inches of water. They had to use a ruler to measure on their own,

They placed the  "bug" on the water near one corner of the container. The surface tension allows the paper to float just like it allows insects to walk on water.  Again, using the toothpick, they weakened the surface tension.  At that quick moment, the water creates a sort of a wave that pushes the paper to move very fast to the other side of the container. 

Here we were testing how strong the water tension can become. Instead of the water spilling outside of the toothpicks, it likes to push the toothpicks apart.  Water prefers to stay together. By placing the drops in the center, we actually opened up the toothpicks to form a star.

The last experiment was to also test the strength of the surface tension.  The kids had to figure out a way to not break the tension as they placed each paper clip on the water dome. 

It became a challenge to see who could placed more paper clips, and keep them afloat.

Big Sister got up to 12 paper clips.  She was curious to see what would happen if she decided to weaken the surface tension.  She dipped her toothpick in liquid detergent again, and gently touched the water. Right away, many of the paper clips fell to the bottom of the cup.  She proved her own predictions!


  1. What brilliant young scientists you have! :)

  2. Lucinda, thank you for your compliment. To be honest with you, science was never my thing. I am a history lover. I am learning to love science with my kids. In fact, I am learning to love a whole lot of things with them!


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