Spinning Eggs

by Deb on March 15, 2012

Eggs

This is something that has been on my list of possible activities literally for years. But I’ve never got to it because it feels so contrived. I mean when would you have a reason to do this? No, it’s just a fun trick, not something you’d ever actually do. Except, first watch the movie.

Now, what are at least two differences you noticed between the two eggs?

Make sure you list them before continuing …

…   …   …

Hopefully you got that

  • Egg 1 spun easily Egg 2 wobbled all over the place.
  • Egg 2 started spinning again after I stopped it.

What do you think could have caused that?

… (thinking time) …

Got it? No? Would you like a clue?

Egg 1 is boiled, Egg 2 is fresh.

Does that help you work it out?

…   …   …

Ok, let’s check your explanation, because you all have one, don’t you?

The Answer

Inside a boiled egg (Egg 1) is solid, but inside a raw egg (Egg 2) is liquid.

Solids keep the same shape and all move together, while liquids take on different shapes and don’t move with their container (the eggshell). It takes them time to get dragged around and once the container stops they will keep moving, like that cup of sticky juice your child slopped all over the floor.

As a solid, Egg 1 all spun together and then stopped when I stopped the eggshell. But Egg 2 took a while to get going and slopped around, and when I stopped the shell the insides kept moving, dragging the shell with them as soon as I let go.

Conclusion

I always thought of this as just a trick, but it’s actually a pretty good activity to show the differences between solids and liquids, which is huge in primary science. Plus it’s more fun than just using a bottle with water, because you can set it up as a mystery first before you pull the bottles out for everyone to play with.

And at the very least, when your 3 year old collects the eggs and can only reach one shelf which is where you happen to be storing the boiled eggs you now have a solution. I smashed a raw egg onto a chopping board yesterday, it didn’t peel easily. But the girls had fun seeing which ones would spin 😀

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