Science Sundays Week 2: Water Density

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This Science Sunday we dove into the world of experimental science, creating a laboratory at the Seaside Center where scientists of all ages could discover. Our question of the day examined whether things float better in the ocean or in a lake. Many different kids had different answers to the question, but all agreed on the fact that the ocean is salty while a lake is not. To further test our guesses, we conducted an experiment. We looked at two cups of tap water. One that we just poured from the spout and the other we added table salt. We then placed a baby carrot into each cup. The carrot in the plain water sank to the bottom of the cup, and the carrot in the salt water floated to the top. When asked why this happened the kids said it was because of the salt, but still could not explain more. I then gave them a scenario that I was told that really helped me to understand the concept of water density. 

Let’s say you are in a room. You need to get from one side of the room to the other side. Is it easier to get to the other side of the room if it is crowded and full of people, or if the room is completely empty? Everyone agrees it is easier to make it through the room if it is empty. So now imagine that the water is the room, the salt particles are the people and the carrot is you, trying to get to the other side of the room. With more salt in the way, the carrot can’t make it to the other side of the room, or in our laboratory, the cup. This is why the carrot with nothing in its way, the fresh water cup, (representing the lake) was able to sink to the bottom, while the carrot with the salt in its way, the salt water cup, (representing the ocean) floated at the top. 

This week we are highlighting young scientist Melek’s lab notebook entry. Great job Melek. Keep on exploring! And if you want to do your own experiment at home, we have included a blank lab notebook entry below too. 

Emma Castiblanco, 2021 Seaside Center Naturalist