I set this experiment up in about 3 minutes for my 3 superheroes and they are STILL laughing and playing as I write this blog post! So easy, so fun and perfect for the warm late winter’s afternoon we have right now in Mid-March. I’m using Pots of Gold since St. Patrick’s Day is tomorrow, but this can be done with any plastic cup or small container and rocks or pennies.
Here’s what you need to get started:
- Bin for the water (I use plastic shoebox bins from the Dollar Store)
- Food coloring (optional – I used green for this activity)
- Candy Kettles (any party store has them seasonally) or any small plastic cup
- Rocks (I painted mine gold for St. Patrick’s Day)
- Pennies (we needed almost 100!)
I set up the tray for them
I had the boys place one gold nugget in the water and watch it sink. Then they placed the kettle in the water and it floated.
Next, I asked them to add the gold to the pot until it sank.
My littlest one loved this. He also practiced his counting! (He can only go up to 5 so I used BIG rocks for him) Looks like the pot is almost about to sink!
Oh no! Too much gold! The pot sank!
The boys had so much fun playing with this! My eldest son used pennies in his pot. It took him over 50 pennies!
I had a BIG mess on the floor. So, I recommend doing this outside 🙂
This activity is a St. Patrick’s version of my original floating activity: What Floats Your Boat?
The Science behind the Activity:
When doing this experiment with older kids, I discuss the concept of buoyancy, which is the ability of an object to float when placed in a fluid. Surface area greatly affects the buoyancy of an object. The larger surface area allows the force (weight of the gold/pennies) to be spread out over a larger area, thus allowing the pot to float even with the “treasures”. The larger surface area displaces more water. This is why a large hull in a ship is able to float on water. And if the ship is floating on salt water (like the ocean) it can carry even more cargo since salt water is denser than pure water. It’s a bit more complicated than my simplified explanation, but hopefully you get the point. And for the little ones, it’s just fun to sink the pots and get wet:)
For more details and to see where I got my idea from, please visit: http://littlebinsforlittlehands.com/st-patricks-day-sink-float-science-experiment-with-pennies/
For more St. Patrick’s Day Science, check out the following activities: