Posted by: unlikelygrad | October 5, 2009

I just want them to use their brains!!

It’s amazing how my freshmen can be dutiful about following directions, but can be amazingly unable to exercise common sense. For example:

(1) In a spectroscopy lab, they collected wavelengths and relative intensity for the peaks found in various atomic spectra. (We had single-element lights out for their usage.) Several said, “We calculated (via Rydberg’s equation) four peaks for hydrogen, but we only see one. Something must be wrong with our data!!” The idea that the other peaks are too small to be seen, if not non-existent, did not occur to them.

(2) In the same experiment, one student made up a table showing wavelengths and relative intensities. At the bottom of the table, she showed average wavelength and average intensity. This is supposed to be useful…how?

(3) In the current experiment, students were supposed to observe chemical reactions and deduce the balanced chemical equation. In one reaction, HCl was added to sodium bicarbonate, which fizzled. At least half a dozen of my students (consulting a table of possible gases) deduced that the gas was HCl gas…never mind that the table says that this is toxic and no one suffered any ill effects…

The problem, of course, is that critical thinking can’t be taught in groups; it has to be done one-on-one. So students whose parents didn’t impart this valuable lesson are pretty well sunk. I hope I can help them. Of course it would help if they actually came to my office hours…

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