Explaining forces to a 10 year old
February 11, 2014 1:32 AM   Subscribe

My 10 year old daughter (Year 6, UK) was recently given homework to "explain how the following works": a) gravity; b) air resistance; c) magnetism; d) upthrust; e) friction. My initial thought was that there is a Nobel prize in the offing if she can truly explain some of these, however, less flippantly, I struggled with how to do this in terms that a 10 year old would understand. Can anyone do any better?

Gravity I think I can handle: mass (or matter) attracts other mass; the more mass, the more gravity (so it is not so much the Earth attracting her, as both her and the Earth attracting each other).

Air resistance is air "particles" hitting the object moving through the air (imagine walking into a blizzard of ping-pong balls). A horizontal sheet of paper falling through the air will hit more air particles and so fall slowly; a vertical sheet of paper will hit less air particles and so fall faster.

Friction is imperfections in two surfaces catching on each other. I used velcro as an extreme example.

Upthrust starts to get a bit more hand-wavey since she hasn't really been taught the concept of density yet. An object placed in water pushes the water out of the way and the water wants to move back into the space occupied by the object. The force of the water trying to move back into the space pushes the object upwards ("why doesn't it push the object downwards" would seem to be the next question following this logic).

My explanation of magnetism doesn't get much further than: there are lots of very small magnetic particles that line up to make a large object magnetic, however this seems a bit like a "turtles all the way down" explanation.

Can anyone do any better?
posted by oclipa to Education (12 answers total) 16 users marked this as a favorite
I suspect you may find that this question means "Please restate what you learned in science class this week", in which case you should not be needing to help with this. Have you tried asking the kid what she thinks the answers are, or what she learned about these things recently?
posted by emilyw at 1:39 AM on February 11, 2014 [9 favorites]

Don't really have time to type but

BBC KS2 Bitesize science is your friend! (And hers, as she can read it and have a go at the activities).

In the long run buy What's physics all about? It's brilliant.

Magnetism is weird: yes, a good explanation for that age group is that magnetic materials are those that are made of molecular structures that act as microscopic magnets that can all line up in the same direction, to make one big overall magnet. Non-magnetic materials don't have the ability for these micro magnets to all line up.
posted by dowcrag at 1:54 AM on February 11, 2014 [2 favorites]

Yes, sorry, this was more revision than homework per se, however the answers she seemed to have picked up in class ("gravity is what pulls you down") don't really seem to answer the question. She understood what the effect was, not how it worked (which is what the question is asking). Maybe I am being pedantic and the teacher had provided a badly worded question, however this set me thinking on how you would actually answer this at the level of a 10 year old (if only for my own interest, since I often find myself getting bogged down in complicated answers that are way too detailed/intricate for her at this stage; I was seriously considering going into details of moving electric charges and spin before I stopped myself).
posted by oclipa at 2:00 AM on February 11, 2014

I am probably projecting my own childhood a bit, but I would caution you from becoming too invested in her having the "right" understanding of these concepts at ten. I remember my own father offering me way too high level understandings of scientific/mathematical concepts as a child and it was really demoralizing. I mainly left these conversations feeling really stupid, when as an adult I can now understand that his explanations were just age inappropriate. I ended up becoming really good at faking understanding when he gave me some high level mini lecture on why the sky is blue, how black holes work, etc., but I became pretty turned off to scientific inquiry overall. I would focus on being curious with her in a more open ended way about things in the world and try to stay closer to her experience, rather than that she "get" some pretty abstract explanation. Especially if you are judging her own explanations/understandings in a "That's right"/"That's wrong" kinda way, which can feel shaming. I absolutely hated those interactions as a kid. Maybe you both could go to a children's science museum and play with some of the concepts directly? If you are ever in San Francisco, The Exploratorium has some great hands on exhibits on gravity and magnetism. Also maybe you could look into some children's books on science and read them together? It seems to me that at this age getting her curious and wondering about the world will take her a lot farther then trying to get her to understand something before she is developmentally ready. If you share your interest in the world with her, she has her whole life to learn scientific theories and concepts in depth. If you belabor it too much now, she may come away thinking she is no good at science or associate it with negative feelings/experiences.
posted by amileighs at 3:26 AM on February 11, 2014 [15 favorites]

Richard Feynman explains magnets to a non-scientist
The video itself might not be good for a 10 year old, but it brings up the interesting idea that magnetism is similar to the electric force which is why you can't pass a solid object through a solid object, why they collide instead.

Other videos in the same series (Fun To Imagine) deal with the other subjects, and are generally better - magnetism is the hardest, and he initially seems a bit grumpy about it, rather than the usual awe and enthusiasm in some of the others)
posted by anonymisc at 4:00 AM on February 11, 2014 [2 favorites]

Sorry to thread-sit, but I think I've maybe given the wrong impression with my question. Yes, I agree that that explaining things too early can put some children off, however all I am really interested in is whether there are better child-friendly explanations of the causes (rather than simply a description of the effects) behind these forces.

My daughter was plainly enthused by the idea that she was attracting the Earth, rather than just the Earth attracting her, which stems from the idea that matter attracts matter; I was wondering if there was a way to provide a similar insight into (in particular) magnetism, but maybe it is not possible to go into any more detail than "magnetism is created by magnets because magnets contain magnets" at this stage.

(ok, backing off now...)
posted by oclipa at 4:12 AM on February 11, 2014

on the go right now, but you can search on www.reddit.com/r/explainlikeim5.




posted by alchemist at 4:59 AM on February 11, 2014

I think upthrust is what we called buoyancy when I was a child, if that helps anyone help the OP.
posted by SandiBeech at 4:59 AM on February 11, 2014

Heya, I'm a physicist, I'll try my best to explain these things in an age appropriate way, though I'm not really used to that, so I might completely miss the mark.

Your explanations for gravity and air resistance are correct and your explanation for friction is good for a 10 year old (friction's quite a difficult one to describe fully as it's a catch-all for a bunch of different effects that slow things down).

A good way of thinking about buoyancy (in my opinion) is to imagine balloons filled with different substances. Say you have a room with air and helium balloons in it, then all of the balloons will be attracted to the floor by gravity. However, (linking back to what she learnt about gravity earlier) the air filled balloons have a stronger attraction than the helium ones so they form a layer below, with the helium balloons floating on top. If you pull a helium balloon down into the air layer, it will float upwards, as the air balloons sink back to the floor.

Using this idea, you should be able explain how a boat floats (a wooden balloon full of air, surrounded by balloons full of water) and why it doesn't matter that a boat has an open top (as long as no balloons full of water get inside, your wooden balloon can have as many holes in it as you want). As you mention, the real answer is about density, but as the balloons all have the same volume, it's really only mass that she'll need to be comfortable with.

As for magnetism: yeah, it's weird, and I'm not sure a truly intuitive explanation exists. Fundamentally when materials have the property of magnetism they create and experience magnetic forces, in just the same way that when materials have a property called mass they create and experience gravitational forces. So how about explaining it as an analogy to gravity (which seems intuitive to people as we're used to it, even though it's just as weird, if not weirder).

Reusing your statement about gravity, we get 'magnets attract other magnets; the stronger the magnets, the greater the force'. That's pretty much all you can say about magnetism without going into a great deal of technical detail. The only difference in the way that magnetism behaves compared to gravity that you'll need to think about is that magnets can push and pull (attract and repel), whereas gravity can only pull. Apart from that, things like the force decreasing with distance, and little objects causing small forces combining to make large objects causing big forces all work in exactly the same way.

As an answer it feels unsatisfying as the 'why' hasn't been addressed, but the 'why' of mass making gravity isn't either, so hopefully it will be helpful.
posted by Ned G at 6:16 AM on February 11, 2014 [3 favorites]

I recently saw this neat demonstration/explanation of gravity by Dan Burns. FYI: it's from a workshop for other physics teachers so there's some material that isn't aimed at students.
posted by JackBurden at 6:37 AM on February 11, 2014

Seconding those who've said that the "right" answer for your daughter is almost certainly to restate what she learned in class this week which, assuming she has a textbook, is probably in the textbook, most likely in bold print or a sidebar.

But to answer the question in the spirit in which you've asked it, maybe check out the Khan Academy videos on the topic? Though those might be a bit above her age level. I can't check them at work, so not sure. Minutephysics has a good video on fundamental forces but I suspect it would go over her head (it was nearly over my head).

A third, joking, answer would be let her play Portal 2 (for friction and gravity anyway).
posted by Wretch729 at 11:09 AM on February 11, 2014

Magic School Bus!

Might actually skew a little young for her, but great, elementary appropriate explanations of all sorts of science things, with experiments and whatnot.
posted by anastasiav at 1:08 PM on February 11, 2014 [1 favorite]

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