Eureka! Exploring the Volume of Objects With Christian Kids Explore Chemistry

The story goes that long ago, a king in the ancient world wanted to commission a crown made of solid gold. He called on a goldsmith and gave him the gold needed for the crown. When the goldsmith brought the completed crown, the king was suspicious. The crown didn’t feel as heavy as the king had expected. Did the goldsmith steal some of the gold for himself? The king had no way to find out because, at the time, no one knew how to measure the volume of an irregularly shaped object.

The king called his wise friend Archimedes to him and asked him to help. Archimedes began to ponder the problem, but he was also stumped. That night when Archimedes sank down into his tub for a bath, he noticed how the water in his very full tub sloshed over the side as his body sank in. Archimedes all of a sudden knew how to determine the volume of the golden crown. He leaped out of the tub, didn’t even stop to dress, and raced away to tell the king of his discovery. Running in to the king’s presence he yelled “Eureka!” (which means “I found it!”). (You can find Archimedes’ story here.)

Volume experiment from Christian Kids Explore Chemistry

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Whether or not the story is true, scientists use similar methods to measure volume today. Ashlyne, Rachel, and I came across a lesson about finding volume with this method in the Christian Kids Explore Chemistry book from Bright Ideas Press. Because we knew the story of Archimedes, we were interested in doing this volume experiment.

Materials we used:

Measuring volume of irregular objects

Graduated measuring glass (The experiment recommended one that would hold more than 300ml. Ours is a 250ml glass, so we used less water starting out and smaller objects to measure.)


Rocks of various sizes

Other objects to measure

The procedure:

We began by measure out 200ml of water in our glass. We were careful to make sure that we had exactly 200 ml.

Measuring volume using the volume of water
Volume of water

We placed one rock into the water and recorded the volume of the water in the glass.

Chemistry experiment with volume

By subtracting the volume of the water by itself (200ml) from the volume of the water containing the rock, we could find the volume of the rock itself. We did the procedure with three different rocks and recorded our results each time. The Christian Kids Explore Chemistry reproducible pages had a chart that I printed off for the girls to record their data.

Kids' chemistry experiment

Comparing the volume of the different rocks along with the size and shape of each was interesting and gave us opportunity to discuss more about the difference between mass and weight.

Hands-on chemistry

The data chart gave extra space to record the volume of an object of your choosing. The girls chose to look at the volume of some ball bearings that we had in the schoolroom- from a previous science experiment. Because the ball bearings were so heavy- but small- we were able to illustrate the mass/weight difference.

Hands-on chemistry experiment

What we learned:

The Christian Kids Explore Chemistry book does a good job explaining this concept of finding volume of an object using the volume of water with and without the object in it. Although we’ve read about the concept before, having the opportunity to actually experiment with the concept really made it “stick.”

You can learn more about volume and other science topics and find lots of great experiments in the Christian Kids Explore Chemistry book and other books in the series.

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