This is an activity for young elementary school students to learn about the concept of density. A slide deck template is attached with a helpful YouTube video embedded to introduce kids to the scientific basics. Below are instructions for conducting a few simple experiments using water to demonstrate density.

Preparation:

You will need the following materials for this presentation:

• A large transparent jar or bowl
• water-soluble food coloring
• vegetable oil
• table salt
• one raw egg
• one hardboiled egg (optional)
• various household/classroom objects (toys, silverware, pencils, etc) that can be submerged in water without damage (optional)

Presentation:

Use the first two slides in the attached slide deck as a template for an introduction of yourself, your organization, and a simple explanation of what you do. The third slide is optional to give students some more basic background on nuclear power if you would like.

Slide 5 contains a brief video to explain the basic concepts of density. You can pause the video at 3:08 in order to begin your experiment. Display slide 6 while conducting the following activities:

1. Pour water into the clear container where the kids can see it until it’s about half full. Bring out the vegetable oil. Ask which liquid the kids think will be denser (sink to the bottom), and which will be less dense and float on the top. Add the water-soluble food coloring a few drops at a time and help the kids observe which liquid it bonds to/where it settles.
2. Empty the container and refill it about halfway with water. Take out the raw egg and ask the kids if they think it will sink or float. Remove the egg and dissolve your table salt in the water (you will need a significant amount – measurement will vary depending on the size of your container, so it may be good to conduct a test run in advance). Explain that adding the salt increases the density of the water and ask the kids if they think the egg will sink or float in the new solution. If wanted, you can also conduct this experiment with a hardboiled egg in parallel.
3. (Optional extra activity) Fill a big container of water (this could be a sink) and let the students drop household/classroom objects of varying densities into the water to observe the difference in behavior. Ask them to guess if the objects will sink or float.

Water Density Slide Deck