Science Experiment for kids – Fun With Density

Today’s Science Experiment for kids was all about


Terms to learn:

Density – Density is basically how tightly matter is crammed together in a material or object.
Matter – Anything that has mass and takes up space is matter.

Main Question to ask first:

Which do you think has more density water, salt water, or oil? Or do you think they are the same?


2 Cups full of Plain Cold Water
1 Cup of Oil
1 Slice of Potato or other objects. Doesn’t have to be a potato.
Large Clear Container
Food Coloring in at least 2 colors
Large Spoon


Add a couple drops of different colors of  food coloring to each cup of water.


First Question to ask:

What will happen when we add salt to water? Will the water level rise?

Take note of the level of water in your cup. And now pour salt in to one of your cups slowly. The salt should dissolve and occupy the same space as the water therefore not raising the water level substantially. The salt fills the voids in between the water molecules. The salt also makes the water more dense.


Second Question:

Which has more density the Salt Water or the Oil? What do you think will happen when they are mixed?

Pour the salt water into your large container and then pour the oil in as well. The oil will float because it has a lower density than the salt water.



Next Question:

What do you think will happen when we add the plain water? Do you think it will mix with the salt water?

Using the back of a spoon or flat object, pour the plain water slowly and carefully into the container. The plain water will create a layer in the middle of the oil and the salt water. It isn’t as dense as the the salt water but still denser than the oil.


Follow up question:

Which has the most density? least?

What is density?


This is the oil floating on top.

Now you can add your solid to the mix and watch it cut through each layer. Test to see which solids will float and on what level they will float.

Which has more density?


  1. Ooooh, this is fabulous! we will be studying density this year. I’m pinning this for future reference.

    Thanks so much!

    Wishing you a lovely day.

  2. Becka, this is so great! My kids would love this and I love how simple it is!

    This will be a fun weekend activity!

  3. This looks messy! My kids would love it!! LOL!

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