Wednesday, November 05, 2014

Science with the Kids: Gravity

Who's ready for some fun, quick, and easy science with the kids? The kids and I had some fun science time last night. I thought I'd share what we did, because this is super easy and the kids genuinely loved it.

First, we did a little experiment. I took a sheet of paper and a little bag of pennies and showed them to the kids.
Materials for experiment #1
I asked them what they thought would happen if I dropped both at the same time. Not surprisingly, the both said that the pennies would hit the ground first. I told them that was their hypothesis, and it was good to have a hypothesis, and that we'd test it. But first, I asked them what they thought the other possibilities were. They quickly got that the paper could hit the ground first. I asked if there was a third possibility, and after thinking for a minute, Pumpkin came up with the idea that the two objects could hit the ground at the same time.

I've done this experiment with other kids (probably 50 kids total, over the years) and Pumpkin is only the second child to come up with that third option, so I'm pretty proud of her.

Then we did the experiment. We counted down from three, and I dropped the pennies and the paper. As they expected, the pennies hit first, while the paper floated down.

I asked them why they thought this was, and they both agreed that it was because the paper was lighter.

Then I asked them how we could test that theory. They didn't have any ideas, so I provided one: I crumpled up the paper and said that if their theory was correct, the pennies should still hit first. They agreed.

Materials for experiment #2
Then I dropped the pennies and the paper together again. This time, the two objects hit at the same time, which just delighted my kids. They were literally jumping up and down with excitement.

I asked whether they had any other ideas about why the pennies hit the ground first in the first experiment but not the second, and to my amazement, Pumpkin got it. She said it was because the air was pushing on the paper and in the second experiment, the paper was smaller so the air couldn't push on it as much. Mr. Snarky had been watching in bemusement up until this point, standing behind the kids. I saw his eyebrows go up when she said that. I think I managed to just smile and say that was a good answer.

In fact, I am very impressed with her answer. I think they covered something similar in science last year at school- they talked about wind as part of their weather module, and she came home with a pinwheel. But still, she was able to take that idea and apply it to something completely different. I was not expecting either kid to figure out why the paper fell more slowly in the first experiment.

After talking about our results a bit, we all watched this really cool video demonstrating the same point with far fancier equipment:

The kids really liked the video, so even if you don't do the experiment, consider showing the video to your kids. I think having done the experiment makes the video more fun, though.

One thing I didn't do that I wish I had done was point out that the people in the control room in the video are a physics professor and a bunch of engineers. They all knew what was going to happen, but they still react to the outcome with the same delight my kids showed during the penny and paper dropping experiments. That's part of the beauty of science!

The entire process-two experiments, discussion, and video watching- took less than 20 minutes. I think Petunia is maybe a little bit young for the experiment, or at least for doing the experiment with an older sister who got the answers faster than she did. However, Petunia still really enjoyed the experiment and the video, and both kids tell me they want to do more family science experiments. I guess I'd better find us some more to do. Feel free to leave suggestions in the comments.


  1. Loved this post! I will definitely try it with my son! Would love it if you would share similar experimenty stuff!
    I have had the solution-solute experiment. He would first have to guess which will dissolve and which won't.
    Then the float-sink experiment. Ice floating really blew him. I started about densities, I guess it should wait!

  2. oh please do more experiments - I'm going to do it with my kids. Are you on Instagram? There's a lady I follow who does really cute and easy crafts.... we follow and do the same but ours are MUCH less cute :)

  3. Anonymous7:26 AM

    This reminds me of when my dad opened a big bottle of soda that had been in the garage when it was freezing outside. The soda was liquid when the bottle was sealed (i.e. pressurized), but froze instantly as soon as he opened it inside. He was surprised himself, until he wrote out the PV=nRT equation and we proved why it worked that way. The equation might be a bit much for your kids (I was in high school), but the 'experiment' is easy. (Amy)

  4. I remember doing one when I was in 3rd or 4th grade, using a thumb tac and a water bottle. If you stick the tack into the bottle and remove it creating a hole, no liquid will come out because of surface tension, and if you make a bigger hole it will come out.

  5. Anonymous1:09 PM

    Experiments that my five year old did in daycare: light a candle, put a glass upside down over it and watch how it goes out because there is no oxygen left.
    Put lit candle on a plate with about a cm (~third of an inch) of water, the candle goes out and the water gets sucked into the glass. The explanation here is a bit tricky, since there are two effects: The smaller one is that the O2 gets burned to co2 and h2o, h2o condenses -> less pressure. The bigger effect is just that the air is hot and cools down quickly after the candle is off, causing the pressure to fall. (I think they told my son the first explanation.)
    There is a website with science experiments for kids I haven't done much, since my kids are only 3 and 5, but Ed Yong recommended it a while ago, so it kind of has to be good.
    Keep us posted if you do more experiments!


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