Do things float in salt water? in fresh water? Why do things float in water?
Question/Hypothesis: Would an egg float in salt water?
Objective of the experiment
To teach children that objects float more readily in salt water because it has greater density than fresh water.
Materials needed for the experiment
- two eggs
- two glasses of water
- spoon to stir
Pour water into two glasses. Add salt in one and stir to dissolve the salt.
Place one egg in each glass. Observe the difference.
Results of the experiment
The egg in the salt water will float while the egg in the fresh water will not.
Salt water is more dense than fresh water. The density of an egg is slightly greater than fresh water, so the egg sinks. The egg is slightly less dense than salt water, so the egg will float in salt water.
So why do things float in salt water? If the density of the water is greater than the density of the object, it will sink.
Additional fun with the experiment
Try this experiment with different small objects to see which will float or sink.
Have your child draw a picture of the experiment. For super bonus points, have your child write the results of the experiment on a card.
The scientific method
- Think of a problem
- Pose a question or formulate a hypothesis
- Collect materials
- Conduct experiment (procedure)
- Reach a conclusion based on the experiment results (the answer to the question)
- Record results
Ask your children: what question would they like answered?