Science Experiment: Which Container Has the Most Water?

 The kids have been asking me to do an experiment. Here's a simple one that's easy to clean up and doesn't require any special ingredients.

First, I put a measured amount of water into five different containers. Then I asked the kids:
What container has the most water in it?

They both came up with a hypothesis.

 Desert Girl thought the container filled to the rim had the most water in it.

 Desert Boy thought that they all looked about equal.

Well, how can we test that?

First he wrote down a list of the containers.

 1. Flower Vase, 2. Widest, 3. Jar, 4. Little cup, 5. Big cup

Then came the fun part: measuring the amount of water for each one.

 Desert Boy had a lot of fun pouring the containers, one by one, into the measuring cup. We discussed fractions and what 1/4 cup and 1/2 cup and 3/4 cup meant.

And our results:

Desert Boy was mostly right in his hypothesis. All the containers held the same amount of water (1/2 cup), except for the flower vase, which only held 1/4 cup.

This experiment could be altered by putting different amounts into different containers, but I wanted the kids to see that the same amount of water looks different based on the shape of the container.

Another alteration could be to put some food coloring into the water to make it even more apparent, but I wanted a super easy clean up so skipped that step.

The next experiment that naturally follows is:

How much water will each container hold?
Step 1: Have the experimenter arrange the containers in order from smallest to largest. This is the hypothesis that each next container will hold more water than the previous one.
Step 2:  Pour water to a defined line (e.g. 1 cup or 2 cup) in a measuring cup.
Step 3: Pour water from measuring cup into container. Record how much water it holds.
Step 4: Continue steps 2 & 3 until the amount all containers hold is recorded.
Step 5: Check results to see if the hypothesis is true.

I thought these experiments might be a little too simple, but they held the kids' attention for half an hour. Plus Desert Boy learned how to correctly read a measuring cup and a little about fractions. He also practiced his writing and recording skills. And Desert Girl, who mainly watched from the sidelines, piped up at the end: "Mom, this was a great experiment."

Hurray!