h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

Just to start it off:

Here are a few ideas that came up from a thread called Science project in a my journal recently:

"I had great fun explaining "gravity" to him a few nights ago. I asked him to touch the four walls of his room, then to touch the floor, and then to touch the ceiling. When he couldn't do it we had a discussion about why that was the case. He asked an interesting question though - why don't we *feel* gravity pushing down on us then?" (Woodpigeon)

"That's a great question Woody! Get him to hang by his hands on a climbing frame, and he'll feel gravity pulling him down. When he's standing on the ground he feels the ground holding/pushing him up. That's where you can bring in Newton's third law if it isn't too advanced for him.

You might just say that when something is standing still, the push of gravity and the push of the floor (or whatever) balance out. Get him to hold something in the air and then let go to demonstrate this."(toxxin)

"A good way of 'feeling' gravity is to lie in a bath as the water drains away." (Potholer)

"Or get him to hold his arms streched out by his sides for a while, he'll really feel it kicking in. Or try a thought experiment: what would it feel like if there wasn't any gravity? "(Malabarista)

I hope you don't sue me for copyright guys.

Alex.

Many years ago when I read Richard Feynman's autobiography, I was impressed by how much importance he attached to the way his father had inspired his fascination with the world around him simply by bringing it to his attention from a very early age. I've tried to follow this principle with my daughter (as soon as she could walk she went into the garden and tried to eat a snail...). She's now 10 and has an intense interest in science and never stops asking questions (fortunately she's given up trying to eat the wildlife) but what she especially likes doing is finding out the answers for herself. I think the best thing a parent can do is encourage the child's sense of wonder rather than necessarily providing precise answers.

(it's taken 30 minutes to type this because I'm watching the restaurant at the end of the universe at the moment..)

I think the best way to explain gravity is the Newtonian way, as a force that pulls us downward.

I think it is very hard to explain it the Einsteinian way, as a bending of space so that we are not pulled towards the earth but that's just the way the space goes.

I'd recommend people start with the simpler idea of things being attracted to each other, even though it is only a simplification.

Terry Pratchett describes the teaching of Science as "lies to children". It's a question of picking which lie fits the situation the best, as we can never hope to explain the full complexity of the real world. We start out with a little lie: "Things fall down", then go on to a bigger lie "Objects attract each other" and then to "objects move towards each other because that is their natural state, in which no force acts on them" and then, no doubt, to supergravity or some such.

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I agree with encouraging a child's sense of wonder. As a parent one can introduce them to new objects a see what they make of them e.g. a triangular prism or something similar from a gift shop.

I don't see any harm in finding out the answers to the questions our children ask, that way we are learning together.

There will always be times where we have to admit that we don't know. Well until we find out later....


Alex.

When I was but a wee bairn, I found that one of the most visibly understandable ways of comprehending it was the 'rubber sheet' universe. In this, the universe is seen as an infinite and infinitely flexible flat rubber sheet. Every object on this rubber sheet makes an indentation relative to its mass. If you now imagine an object travelling in a straight line across the sheet, it will be deflected and possibly trapped by the indentations created by the larger bodies. This approach isn't perfect, but it does display the idea of objects being attracted to each other rather nicely, as well as showing how the depth of each body's 'gravity well' equates to its mass, as opposed to its physical size.

The only problem, of course, is then trying to translate this two-dimensional universe into three dimensions.

Yes, we do something like that in lessons using pink lycra.

Hey Alex. I'm flattered that you quote my reply at such length. As a Cognitive Scientist, child psychology comes into my field. Consequently, I have the occasional intuition as to how something might be explained to the very young. Did I mention my square bubble-blowing 'ring'?

toxx