Monday, September 04, 2006

I HATE ChemSkillBuilder

ChemSkillBuilder is a website the James Madison University deparment of Chemistry enlists as a teaching tool. It "algorithmically" (an exceptionally fancy word for "automatic") generates problems for students to solve and learn from. I am merely frustrated.

The concept makes sense--have a computer generate conversion problems automatically and simply. However, it is riddled bugs and technical errors; things that hurt my grade without true cause or even honest grading.

Take, for example, this problem (paraphrased):
Convert 20 mL of to grams using 6.6g/mL as a conversion factor.

Simple conversion. Note that the 20 has no decimal on the end, lending it one significant figure. Multiply the two numbers together, producing a result of 132g. Round this for the single "sig fig," and 100 is left.


So, I figure they may have not wanted me to round for sig figs. After all, 20mL only has one sig fig, 20. mL has two. I input 132... and it turns out the proper number of sig figs is 2.

What?! From the 20? It was not a "20.," it was a "20". I was just cheated points for trying to solve the problem correctly.

Another problem, paraphrased, but including the original error:
Convert 114 l into gallons.

114 "l?" What is an "l?" I learned that "L" was the correct symbol for liters, but I've never seen "l" used for some unit. Perhaps that's an uppercase "i..." a disjointed "1?" Maybe it's my doom!

I did guess correctly, they meant "L," but the contradiction between using "l" and "L" has infurated me.

A semester of this?


Anonymous Anonymous said...

Putting a decimal place after the '20' is important to retain its signifigant figures.
ie. 20, would only have one.

It's really supposed to be expressed in sci notation. 20. would be 2.0E1
if you simply do the problem using scientific notation it is much easier.

I hate Chem skill builder too btw. [math xl also]
Tests should be done in class.

Thursday, September 21, 2006 8:06:00 PM  

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