Yesterday we had a blast experimenting with eggs. We took two glasses, one glass had plain water from the sink, in the other glass we added LOTS of salt to the water. First, we put the egg in the plain water and the egg sunk right away, then we took the other egg and placed it in the salt water. This egg floated because the water became more dense when we added salt to it. I had the girls take their science notebooks and draw their hypothesis before we did the experiment, then they drew what actually happened afterwards.
Then we took turns placing the egg in the middle of our hand and squeezing with all our might. We weren’t able to crack the egg as long as it was in the middle of our palm. I explained, by completely surrounding the egg with your hand, the pressure you apply by squeezing is distributed evenly all over the egg. However, eggs do not stand up well to uneven forces which is why they crack easily on the side of a bowl. This also explains how a hen can sit on an egg and not break it, but a tiny little chick can break through the eggshell – the weight of the hen is evenly distributed over the egg, while the pecking of the chick is an uneven force directed at just one spot on the egg.
For our last experiment with our white little egg, we took a glass of vinegar and placed the egg inside. Again I had the girls draw two pictures, one with what they thought would happen to the egg and one for what actually happened. We left the egg in the vinegar for a day and a half. The girls were surprised this morning to see that the vinegar had made the egg soft like a water balloon! I explained that the egg-shell is porous, this lets the growing embryo get oxygen, it will also let things through like pollutants and even the vinegar, which is an acid. By soaking the egg overnight in vinegar it became soft and pliable.
The girls gave these science experiments Five Stars!