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Q & A: Energy for 2nd graders

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Most recent answer: 10/22/2007
Q:
We have a project to do and we need to know what we can teach 2nd graders about energy? can you help?
- Isaac, and class mates (age 12)
Greencastle, Pa
A:
That sounds like a nice project. I think that you can teach 2nd graders something about energy conservation. In other words, you can show them that when one form of energy is reduced another increases. Of course, you can only show this for a few forms. More importantly, they have no prior reason to call different forms of energy the same thing. So I think the demonstration that kinetic energy can go to potential energy or that large scale energies can be lost as things heat up or that light absorption leaves things hotter, etc should come first. That would get the idea across that something or other about these effects is in common, changing forms but not going away. Then maybe you can say that this something gets called energy. That way the idea would be first, and mere names second.

Here are some examples:

bouncing ball, swinging pendulum, .... When the thing is high it goes slow, when it's low it goes fast. As if somehow you could trade height for speed. But then it seems that gradually both the height and the speed run down.

Show that the same thing (called friction) that tends to make things stop sliding or bouncing leaves them a little hotter.

Show crank-powered generator and light. Note that you could also power generator with fallling stuff, like a water wheel. Draw connections with height/speed.

Note that the light feels warm- draw connections with warmth from friction.

Note that batteries run down- and you can charge them up with a crank-powered generator.

So by this point it may be OK to say that you're talking about different forms of energy.

Maybe show some chemical energy- burn something, get heat and light, maybe run a toy steam engine. You could even use it to lift things. You can also talk about energy contained in food here, and how the body uses it to keep warm and to do stuff like run around and lift things. 2nd graders have lots of energy themselves (except when they don't), and the foods they eat have a lot to do with that.

Now you may be ready to ask if there's usable chemical energy stored in water- if it will burn. When they figure out the answer is no, they will be more educationally advanced than certain prominent politicians who say that we can obtain our future chemical energy from the hydrogen in water.

Mike W.

(published on 10/22/2007)

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