Here’s a great project for pre-K kids. They can cut the fish out of paper or foam, pour the water and put a drop of soap behind the fish to make it “zoom.”
My original post and written directions for zooming fish can be found by clicking here.
If you’ve done an experiment where you drip water onto a penny, or made Tie Dye Milk, you know what surface tension looks like here on Earth. How does it look in space?
Here’s an amazing video demonstrating how the surface tension of water looks in zero gravity on the international space station. Fascinating!
This is one of my kids’ favorite science experiments of all time and could not be easier to do.
Food coloring isn’t just for frosting any more! You will be amazed as you watch the forces of surface tension at work in this “brilliant” experiment.
All you’ll need is a small, shallow dish or plate, milk (2% or whole milk work best, but skim milk works too,) dishwashing liquid, Q-tips and food coloring.
I would recommend putting down newspaper and wearing an old shirt, since food coloring stains. You can make a lab coat from an old button-down shirt, by writing your name on the pocket with permanent marker.
First, add enough milk to cover the bottom of the dish. In a separate small container, mix together about a half cup of water with a squirt of dish-soap (a teaspoon or so.) Put several drops of different colored food coloring into the milk (maybe two drops of each color.)
Dip a Q-tip into the dish-soap mixture and then touch the Q-tip to the milk. You don’t need to stir! The detergent will break the surface tension of the milk and the food coloring will swirl around in interesting patterns, as if by magic.
Play with it! You can keep re-wetting your Q-tip with soapy water and touching it to the milk. If you want to, compare how the experiment works with skim milk versus whole milk. Sixth-graders will love it as much as two-year olds!
Now, draw a picture in your science notebook of how the milk looked before and after you touched it with the Q-tip! Take a picture of it and tape it your notebook! Describe what happened with words or pictures.
What Happened? Imagine that surface of liquids is a stretched elastic skin, like the surface of a balloon full of air. The scientific name for the way the “skin” of a liquid holds together is surface tension. When the skin of the liquid is broken, whatever is underneath will be able to escape, like the air rushing out of a balloon.
In this experiment, the surface of milk is like the elastic skin and dish detergent is what breaks the “skin” of the milk, sort of like a pin popping a balloon. Food coloring and more milk then escape from underneath the milk’s surface, swirling to the top.
Click here to watch my video on how to make tie-dye milk.
Here’s a fun, easy science project that I discovered a few years ago on pbskids.org/dragonflytv. My children will do it again and again. Even my three year-old joined in, cutting up construction paper into “fish food” and throwing it into the water.
You will need some sort of pan for water (a cake pan will work), construction paper, scissors, and dish soap. Have your child cut out some fish shapes from the paper (around two inches long works well.) See the photo below. Then, have them cut a small slit in the back of the tail. Put a few inches of water in the pan and add the fish. Before the paper soaks up too much water, have your child add a drop of dish soap behind the fish. The fish should zoom across the water. You will have to add fresh water tothe pan if you want to repeat the experiment.
The soap breaks the surface tension of the water. Tell your child to imagine that the surface of the water is a sheet of fabric and the soap is a pair of scissors. The soap cuts through the water, pushing the fish ahead of it. For a more scientific explanation, have your child look up surface tension or visit the dragonfly tv website!
Don’t forget those science notebooks! Have your children write the date, “surface tension” and record their results. They can try using different liquids (like lemon juice) to see if they will break the surface tension. My kids made some fish out of that foam that is used for craft projects so that they wouldn’t soak up the water! Hopefully, the zooming fish will keep your child interested and busy for a while! Click here to see a video on how to make zooming fish.