As the students continue to experiment with objects and materials to see what will float and what will sink, this exercise will demonstrate whether an Egg will sink or float in both fresh water and salt water.
Materials:
- Table salt
- Two containers
- A Tablespoon
- Warm tap water
- 2 Eggs (courtesy of the Trevose Day School hens)
To begin, we will fill both containers with warm tap water. Our excited experimenters make a hypothesis on whether the Egg will sink or float.
The majority of the children had guessed right, the egg simply sunk to the bottom of the container filled with tap water.
We decided to test the egg in the container that had the salt water next. This test had some of our class torn regarding what would actually happen. Many of the children thought that the egg would sink again, while some thought that there was a chance that the egg could float.
The children added two tablespoons of salt to the other container of water and stirred it until the salt had dissolved in the water.
A child then carefully placed the other egg in the container. To our surprise, the egg also sunk.
Can you believe it? We could not - the egg should have floated! The important lesson for the children was trial and error. Not all science experiments will go as anticipated. This is why many scientists continually test and retest to rule out and find out different factors that may affect the result. The students agreed that if we added more salt to the water we would have had a more successful experiment.
The children discovered through experimentation that salt water is heavier than plain tap water. The weight of the egg does not have to push away as much water to make space for itself, therefore it floats. This is a fabulous example of buoyancy!
