Potions and water play are some of my daughter’s favorite ways to play. Ā They’re a great way for her to learn about science concepts, too. Ā Today it’s all about viscosity. Ā It’s a big word for a four year old preschooler, but I’ve realized that I want to introduce my daughter to some of the real terms used in science. Ā So we demonstrated viscosity with thick and thin liquid potion play. Ā This V is for Viscosity post is part of aĀ fun A-Z STEM learning series, too. Ā This post contains affiliate links.

What is Viscosity?
Viscosity can be seen as theĀ of thickness of aĀ liquid. Ā It’s a measure of how the molecules inside the liquid respond to stress. Ā A highly viscous liquid, like honey, doesn’t deform as easily as a low viscosity liquid, like water, when under stress.
Let’s visualize viscosity… Ā Imagine the liquid as a bucket filled with ping pong balls. Ā Pretend the ping pong balls are molecules. Ā If you put your hand in the bucket, those ping pong balls move out of the way really easily. Ā This bucket would be a low viscosity fluid. Ā Now imagine the bucket is filled with bowling balls. Ā It takes a lot of effort to move those molecules. Ā This bucket behaves like a high viscosity liquid.
Viscosity Play
To demonstrate how viscosity works, The Babe did a little potion play. Ā Mixing and pouring and pipetting (guessing that’s not a word…) with fluids of different viscosities. Ā I chose milk and oil because she’s familiar with them. Ā Then I picked condensed milk and castor oil asĀ higher viscosity versions of them.
Supplies Needed
- Fat free milk
- Sweetened, condensed milk
- Vegetable oil
- Castor Oil
- Tray to catch the mess
- Cups or other things to pour from / to
- Pipettes {affiliate}
- Paint palettes {affiliate}
First up was playing with the liquids with the disposable pipettes. Ā They’re some of our favorite supplies for science and art projects. Ā They’re kind of sneaky too. Ā If you have an expensive material in one of your projects, these make it go a long way because they can only suck up so much at once. Ā Perfect for baking soda / vinegar reactions because it extends the reaction.
Next was pouring the liquids from cup to cup. Ā I wish I had gotten some pictures of her face when she poured the vegetable oil. Ā She was soooo surprised by how fast it came out. Ā Then she started giggling when the condensed milk went way moreĀ slowly.
Finally, she experienced some mixing… Ā “I didn’t know THAT would happen!” she said when the milk wouldn’t mix with the oil.
Some Questions to Ask
While we were playing viscosity potions, we had some engaging conversations. Ā I’m serious, she really was into it… Ā The Babe enjoyed experiencing how the different liquids worked and I asked her some questions to get her scientist thinking going.
- Before pouring or touching the liquids, which do you think is the thickest? Ā The thinnest? Ā (This is where I first introduced the word viscosity.)
- What do the liquids feel like? Ā How are they different? Ā How are they the same?
- Which is the hardest to move through the pipette? Ā What can you do to make it easier?
- What do you think will happen when they mix together? Ā (You can talk about miscibility, the ability for liquids to form a homogenous solution… Milk and oil don’t mix.)
A-Z STEM
This V is for Viscosity post is a part of a fun learning series called A-Z STEM. Ā 26 letters full of science, technology, engineering & math topics. Ā Click through to Little Bins for Little Hands to see all of the activities.
For even more STEM activity ideas, check out the Left Brain Craft Brain STEM Pinterest board.





