This is a fun little activity that the younger scientists really love and is a great addition to your next science themed birthday party. The materials required for this activity are very inexpensive and almost everything can probably be found around your house. Gather your birthday party guests and tell them your are going to teach them the ancient art of slicing water in half!
Food coloring – I like to have multiple colors
Drinking straw for each birthday party guests
One sheet of wax paper for each guest
Place a drop of food coloring into each cup of water. Mix until all of the water is evenly colored. Make up several cups of different colors. The children typically enjoy being able to choose the color they want for the activity.
Demonstrate to the birthday party guests how to put their straw into the water and then hold their finger over one end to keep the water inside. Then have the guests carefully place a few drops of the colored water on to their piece of waxed paper. Have the guests observe the circular shape of the drops.
Instruct the guests to use the toothpick and cut the water drops in half.
Now have them use the drinking straw to blow the drops back together.
Allow some time for the birthday party guests to explore the properties of the water. Encourage them to try different colors of water and ask them to hypothesize if the different colors of water will act differently.
The surface tension of water draws the water molecules within a drop toward one another. The molecules in the outer layer are drawn in toward the center of the drop, giving the drop its rounded shape. The surface tension that holds the water in this shape affected how the water acted when you exerted force on it with the toothpick and the straw.
Make This An Experiment:
Try different temperatures of water.
Try the test on different types of surfaces.
Try different types of liquids and see if they act the same as the colored water.