Science experiments don't need to be complicated! A water drop race is a simple science project is a great was to pass the time when you need a quick distraction for your kids. It can be part of an in-depth classroom exploration into the concept of surface tension and molecule cohesion.
What is Surface Tension?
Surface tension is
the property of the surface of a liquid that allows it to resist an external force, due to the cohesive nature of its molecules.
The cohesive forces between liquid molecules are responsible for the phenomenon known as surface tension. The molecules at the surface of a glass of water do not have other water molecules on all sides of them and consequently they cohere more strongly to those directly associated with them.USGA
A classic kids surface tension experiment is the one where you drip water drop by drop onto a penny. You can also observe surface tension by floating a paper clip on the surface of water.
Bugs also use surface tension to hang out on ponds and streams. Leaves during a rain storm also demonstrate water's cohesive nature.
For this water drop race experiment, surface tension is responsible for the spherical shape of the water droplets. The waxy paper keeps the water from being absorbed away by the surface they sit on.
However, even if your child is too young to grasp the concepts of surface tension and the bonding properties of water molecules, it's still a super fun indoor activity that will make kids say, "Cool!!!"
Water Drop Surface Tension Experiment
How to conduct water drop races
- Gather your materials
You will need:
one straw per scientist
glass of water
wax paper or parchment paper
- Set up your station
Set out a large piece of waxed paper on a flat surface. This is your race track. If you like, mark out a starting and finishing line.
Using the water dropper, transfer several drops of water to the starting line.
As young scientists continue to experiment, they may want to explore using larger and smaller drops.
- Start the experiment!
With a straw, young scientists attempt to blow their water drop from the starting line to the finishing line.
Kids will start to notice ways in which they can control their water drops. Young scientists can explore surface tension strength by blowing air through the straw extra hard, which will cause larger water drops break up into smaller water beads.
Kids will also learn how to blow water beads together to merge them into larger droplets. No doubt, they will have fun sucking water drops up the straw and blowing them back out! My kid loved blowing his off the table to "plop" on the floor! (It's just water, after all.)
Whether or not you use this surface tension experiment to go into depth about how water molecules, tension and cohesion work, water drop races provide lots of entertainment!
I absolutely loved how this project has the added bonus of keeping the kids busy for an extended period of time without a lot parental involvement. And because it's just a small amount of water that is used, you won't have to worry about everything getting wet or the kids making a big mess to clean up!
More water experiments
- Water refraction is just like magic!
- Amaze your kids with a leak proof hole in a bag!
- Make a coin jump off a bottle
- All our favorite indoor water activities
I First Published this idea 3/16/09.