Monday, April 12, 2010

Chemical Christmas

Today was a good day at school.

I'd ordered some science supplies for all my classes and they arrived today. Well, not really today, but we've been on break, so I got them today.

The majority of them was Chemistry supplies, but there was some Bio stuff in there too (an electrophoresis kit and some frogs to dissect). Getting boxes full of SCIENCE is just fun. Especially since I've centered the vast majority of my demonstrations around the best type: Explosions.

My Chem class really isn't up to the proper section for reactions yet. We're still slogging out way through bonding, and I keep telling them we need to learn what bonds are before we start making and breaking them. We're getting there, but not quite yet.

However, I just couldn't help myself from doing a demonstration. One of the bits I'd gotten was calcium carbide which, when mixed with water, forms acetylene gas. The way I've seen this demonstration done previously was in a bottle into which a few small chunks were placed. They fizz and give off some gas, and then are ignited with a spark generator making a fantastic boom. All of my students jumped. This is all I did.

When I actually do the demonstration in the proper section, there's a further component to it: Instead of just dumping in a small amount, a heaping spoonful is tossed in. When the spark igniter is hit, absolutely nothing happens. The reason is that the acetylene gas pushes out all the air and without a proper stoichiometric balance, ignition can't take place. The students, meanwhile, are ducking under their desks.

I can't wait to get up to the proper sections to play with the rest of it.

Oh yeah, and I finally got a balance for my penny lab.

1 comment:

Ibid said...

I'd have to disagree with the idea that you need the basics before you jump to the labs. It's been my experience that the students have a "why does this matter" question in their heads even if they don't say it.
I compare learning to growing crystals. You can provide the materials to grow the crystal from, but before it'll start growing it often needs a seed to form around. A flake of diamond for artificial diamonds or a bit of dust for snowflakes.
History classes were largely a pile of facts to memorize and spit back without much real understanding. But an episode of Quantum Leap planted the date of the Kennedy assassination in my head. From that I was able to build most 20th century history and it's relation to that event.
In math I started with an equation to figure the centripetal force of an object in geo-synch orbit and broke it down to understand how the equation worked and how to rebuild it. Had I started from the other direction, learning the bits and putting them together to make some later equation, the bits wouldn't have had a reason to stay in my head.
When learning a new programming language I do "hello, world" and then jump to something much harder. I have to learn all the new features to build the hard program. If I tried to read the book first the commands would have a much harder time sticking.

I feel the same applies with chemistry. Sure, there's some "hello, world" stuff they need, such as the anatomy of the elements and the Periodic Table, but then you blow shit up to get their attention, then go back and spell out why shit blows up.

Your demonstration should be extremely valuable in getting them to pay attention and then explaining why the reaction happens. I wish I could be there.