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As a former chemistry teacher I would say you cannot overemphasize an understanding of dimensional analysis.
For kids who don't see the point, ask them "backwards" questions such as how many feet are in an inch?
Also, have them do long chains such as determining how many centimeters in a mile. It's good to have figured these out in advance yourself so your student is instantly rewarded if they get the right answer.
Tuesday, July 17, 2007
dimensional analysis advice from Susan J
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13 comments:
I managed to pass both intro chemistry and intro physics in college without learning anything at all about either subject just by being able to manipulate dimensions to arrive at an answer for exam questions. In one semester of Chem I even made a B and had no clue about the actual subject matter.
good grief!
well.... I'm glad to hear it
that was my intuition about these things
the instant I learned them I thought: THESE ARE GOLD
kinda like CROSS MULTIPLICATION
don't tell Steve I said that!
long time lurker here.
Gary, your comment is very revealing. Dimensional analysis is a deceptively powerful technique, and it should typically be your first defense against wrong answers. On multiple choice type tests, it can sometimes get you all the right answers.
Dimensional analysis is a deceptively powerful technique, and it should typically be your first defense against wrong answers.
not so defensive to those of us who did not get a decent math education!
hi, longtime lurker!
It's interesting, because in another way unit multipliers are just algebra.
Except for having to remember how many units there are in something. I can never remember how many feet there in a mile (NZ is metric).
5280!
Saxon has you spend A LOT of time using unit multipliers to convert between metric & English customary.
Is it English customary??
1 mile = 5280 feet = 1760 yards = 8 furlongs = 320 rods.
Unless it's a nautical mile, which is 1852 meters (precisely), 6076.115 ft, or quite close to 1 minute of longitude at the equator (its original definition).
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