Sink or Float?

Posted on Oct 8 2013 in Hearts and Hands by admin

In this new, semi-weekly feature, Michelle Crooker, a veteran homeschooling mom and writer of the blog “Homeschooler on the Edge,” will share a science lesson or field trip to help engage your young student in a hands-on, fascinating learning experience.

 

Today, with the help of Bug (age 5) and Princess (age 8)  we are going to start off with a simple project you can do at home with things that you will most likely already have on hand.

 

Questions:

  • Will an egg sink or float when placed in water?
  • Does it make a difference if it is fresh water or salt water?

 

Materials Needed:

  • Two half-full glasses of fresh water (tap water is fine, and glasses need to be large enough to be able to put an egg in them).

** Note: if you fill the glasses to the top, when you put the egg in, it will spill . . . ask me how I know.

 

Experiment:

1. Take your two glasses and place them side by side on the counter.

Child pouring salt into a glass of water.

 

2. Begin to add heaping teaspoons of salt to one of the glasses.

Spoonful of salt over a glass of water.

 

3. Stir the salt and water combination until it becomes saturated. (Side note: a saturated solution means that no more of whatever you are adding—in this case salt—will dissolve in the liquid).

Glass of salty water with spoon in it.

 

4. Continue to stir until you can no longer see salt floating in the water

Child stirring glass full of salty water.

 

5. Observe the difference between the saltwater solution and the fresh water.

Glass of fresh water.

Fresh Water

Glass of salty water.

Salt Water

 

 

 

 

 

 

 

 

 

 

 

 

6. Make note of their differences. This may seem obvious—the saltwater is cloudy while the freshwater is clear—but this is a good step when starting to do experiments.

 

7. Take your two eggs.

Child holding two eggs  over a glass of fresh water and a glass of salty water.

 

8. Make a prediction.

Bug’s prediction: Both eggs will float.

Princess’s prediction: Both eggs will sink.

 

9. Result:

The egg in the saltwater floats. The egg in the freshwater sinks.

An egg in a glass of salty water that is floating. An egg is a glass of fresh water that has sunk to the bottom.

 

Why does this work?

The simple answer is density. When you added the salt to the water and mixed it in, you changed its density. Saltwater is more dense than freshwater; therefore, things that may not be able to float in freshwater, can float in salt water.

Have you ever been to a pool or freshwater lake? Have you ever been to the ocean?

Which one is easier to float in? People (like eggs) can float more easily in saltwater. Isn’t it nice that God made it that way—especially since so much of the earth is covered in salt water?

 

Reference

The Usborne Internet-linked First Encyclopedia of Science, Rachel Firth, Scholastic, 2001

 

Michelle, a Virginia native, currently lives in Pennsylvania with her husband and three children. Active in Scouts, area homeschool groups, and with her family, she can be found on her blog, “Homeschooler on the Edge,” as well as Facebook, Twitter, and Pinterest.

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