We did a Saltwater Sink or Float experiment to go along with our ocean unit. It’s an easy experiment to do with young scientists because the results are immediate and there are lots of ways to manipulate the variables. There’s also a lot of skills that come into play. Let’s dive in.

Ocean Unit Science Experiment - Saltwater Sink or Float

We had read about the extra-salty Dead Sea and how people can float in it like in a chlorinated pool. For this experiment we tested what effect salt would have on different objects.

Setting up our saltwater experiment

We gathered a few items along with a measuring cup and scoop, sea salt, bowls and of course lots of towels. We used a penny, stone, plastic octopus, and egg.

I drew a chart on the dry erase board and he made predictions about what would happen. I don’t shy away from using words like “hypothesis” with my 4-year-old. He knows what it means and can almost pronounce it correctly.

Pour two cups of water

Next we filled up the measuring cup with two cups of water. Now, you can do this in 5 seconds yourself at the sink, but the kids love pouring water, especially from big, clanky glass containers. But they’re learning important stuff about measurement too. Be patient and let them pour!

We tested all the objects in the “control” freshwater. (This was the first time he’d heard this term and he could easily understand it’s meaning as it contrasted against the saltwater.) We started adding the salt. I think we used about a cup to get the egg to float.

Add salt

It worked!

The eggs floats in saltwater

We kept adding salt and got the octopus to float a little bit. You could try different objects to see if anything else is float-able in saltwater.

Close Observation - Saltwater Experiment

I liked this saltwater experiment because it provided good practice of the scientific method, making charts, measurement, and some general understanding about density.

Of course, you might be wondering what the little sister did while we were busy.

Sea Salt Sensory Play

She did her own Sea Salt Sensory Scoop (i.e. she played with the salt)

It’s totally a thing.

Hope you’ll try this simple experiment with your young scientist. I’m working on a wrap up of our entire ocean unit– it might even be up tomorrow!

Science Experiment for Ocean Unit - Saltwater Sink or Float - Floating Egg Experiment

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