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Re: Mini-volcano



On 11/11/01 2:41 PM, Greg Darakjian wrote:

Learning by doing
is far better than learning through videos.

I wonder if this was directed at my "watch a video of a volcano" comment. If
so, you misunderstood me. I was trying to say that watching a video of a
real volcano in action (or several videos, since there are different kinds
of eruptions) was better than doing the ammonium dichromate demo to
illustrate the formation of the lava cone (or whatever it's called), given
the nature of the chemicals.

If you are teaching chemistry and talking about decompostion reactions, then
perhaps the demo is warranted. It would be even better if you had a way of
trapping some of the water vapour to show one of the other products of the
decomposition. You could even tape the demo, and after the students have
watched the real thing you could do a slo-mo, play-by-play analysis.

Earlier in your message, you wrote:

Part of doing any laboratory activity is learning to
follow safety standards and recognizing the hazards and the consequences of
whatever we are doing and taking the proper precautions.

For this particular demo (not demos in general), I would submit that if you
are producing a beaker of hazardous waste for the sake of a neat demo, you
are not recognizing the consequences of what you are doing.

Think about it -- YOU are performing the demo, not the kids. They watch and
ooh/ahh, it's over and you have a mess to clean up. Wouldn't it be better to
substitute safer chemicals and let the kids run the reactions (plural
because it would be easy to come up with several)?

Don't get me wrong, I am one who loves whiz-bang demos and I have performed
many that were only peripherally related to the subject matter at hand (e.g.
I used to be able to come up with an excuse for an explosion for almost any
course I taught, I've calmed down a bit lately). I personally like watching
videos so I can get ideas of things to do in class, and I would never
substitute a video for real student experience. It's just that I think demos
like the ammonium dichromate volcano are dinosaurs -- good for those by-gone
days when we didn't worry as much about (or didn't know about) some of the
nastier chemicals.

Anyway, I'm sure all of this is better suited to the CHEMED-L list rather
than this one. Perhaps we should let it drop -- the original poster got more
than he wanted!

Mike
--
Michael Porter
Colonel By Secondary School
Ottawa, Ontario, Canada