This year the kids are learning all about the different ecosystems. This week’s ecosystem is Oceans. This just happens to be my favorite ecosystem.
We had the pleasure of experiencing a few years on the Aegean Sea. We spent nearly every summer day at our favorite beach just down the road from our house. We also drank our fair share of sea water – yuck! – when snorkeling & swimming around. The activities we did today were pretty fun and they were a reminder of all of the time we spent practically living at the beach.
The first experiment was to recreate the ocean in a glass of water. This required a lot of salt. The kids were encouraged to taste this shockingly, brackish beverage. Oh yes, memories came flooding back to us of all the times we accidentally licked our lips while at the beach. I admit, I was giggling as they each tasted the water and ran to the sink to rinse out their mouths. Hard not to, really.
Boys! They know what it tastes like and they still want to try it. Tristan took a small drink, but Gavin simply stuck the tip of his finger in the water and touched it to his tongue. I love their antics!
Next, Gavin filled two big bowls (buckets) up 2/3 full of tap water. Then Tristan and Gavin measured out 15 tablespoons of salt into one bucket. They placed one egg into the fresh water and another into the salt (ocean) water. We all decided the ocean needed a bit more salt, since our buckets weren’t clear, we couldn’t see the floating egg really well (another activity with too much white).
After just 5 tablespoons more of salt, that egg practically jumped out of the bowl. This demonstration helps to understand why we float so much better in the ocean than in fresh water. It also helps us to visualize just how much salt our oceans have (3% if you’re interested). We also briefly discussed the Dead Sea and what that must feel like. After learning that it is nine times saltier, Tristan had to test that out too, by adding more salt to the first solution (9 more T. to the glass of salt water). Sadly, he did not taste the water this time, but he did place an egg in the water to check its buoyancy. Very curious boys here, I must say.
And for our last trick . . . salt crystals. The boys boiled two cups of water and were supposed to slowly add salt, a tablespoon at a time, to the new solution. This time the goal was to dissolve as much salt as possible into the water. Unfortunately, Tristan jumped ahead a little bit and added the salt a little too fast. That turned out to be another lesson – of solubility. We re-did this step, slower the second time, making sure each tablespoon dissolved before adding another. Then, Tristan tied a string to a pencil and Gavin helped to measure the length of the dangling paperclip on the string from the bottom of the glass. After we added the slightly cooled water, we placed the glass in the window. Now all we have to do is wait for the water to slowly evaporate and viola, we will have accumulated salt crystals along the paperclip. Note: the glass is supposed to sit in a sunny window, but . . . we don’t have any of those yet.