First and Second grade students continue to experiment as they investigate the oceans!
Buoyancy of Salt Water Experiment
Guiding Question: What does the word “buoyancy” mean? It means having the ability or tendency to float. Why is it easier to swim in salt water than in fresh water? Discuss with students any experience they have had swimming in an ocean and compare it to swimming in a pool. Objects float more easily in salt water because salt water is “thicker” or denser. There is 1 ounce of salt in every 35 ounces of water in the ocean. In the Dead Sea the water is so salty that when the water is evaporated by the sun, the salt that is left forms hard white columns and lumps.
Materials Needed:
Two identical glasses or clear plastic cups
Tap water
Salt water (prepare some ahead of time by adding 1 tablespoon of salt to 1 cup of water) Make sure that all of the salt dissolves.
Two fresh eggs
Data collection sheet for students
Procedure:
1. Fill one cup with tap water and the second cup with an equal amount of salt water.
2. Have students predict what will happen when you place an egg in the tap water. They should fill this in on their collection sheet.
3. Place the egg in the tap water. What happens? Record the results.
4. Have students predict what will happen when you put the other egg in the salt water. Have them record their predictions.
5. Place the egg in the cup with salt water. What happens? Students should record the results. If the egg doesn’t float add more salt.
6. Have students write their conclusions on the collection sheet.
Extensions: Try adding more salt. The egg should float higher in the cup.
Ask students how the amount of salt in water would affect a person’s ability to swim.
Buoyancy of Salt Water Experiment
Guiding Question: What does the word “buoyancy” mean? It means having the ability or tendency to float. Why is it easier to swim in salt water than in fresh water? Discuss with students any experience they have had swimming in an ocean and compare it to swimming in a pool. Objects float more easily in salt water because salt water is “thicker” or denser. There is 1 ounce of salt in every 35 ounces of water in the ocean. In the Dead Sea the water is so salty that when the water is evaporated by the sun, the salt that is left forms hard white columns and lumps.
Materials Needed:
Two identical glasses or clear plastic cups
Tap water
Salt water (prepare some ahead of time by adding 1 tablespoon of salt to 1 cup of water) Make sure that all of the salt dissolves.
Two fresh eggs
Data collection sheet for students
Procedure:
1. Fill one cup with tap water and the second cup with an equal amount of salt water.
2. Have students predict what will happen when you place an egg in the tap water. They should fill this in on their collection sheet.
3. Place the egg in the tap water. What happens? Record the results.
4. Have students predict what will happen when you put the other egg in the salt water. Have them record their predictions.
5. Place the egg in the cup with salt water. What happens? Students should record the results. If the egg doesn’t float add more salt.
6. Have students write their conclusions on the collection sheet.
Extensions: Try adding more salt. The egg should float higher in the cup.
Ask students how the amount of salt in water would affect a person’s ability to swim.