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Classroom Chromatography Effective instruction in chemiral principles often requires the uir. olnnnlogies and drmonscrations. While traching underaradunte lnrtrumantnl analysi. this apring, it occurred tu me that rhromncoaraphy could he drmonstratrd by rneanr of n rlas? partir~nnrionrxpcrlmrnt in which t he classnum is the rhnmatmraphrr column and thestudcntsnre rhr molcrulrs .. t o be separatedl The room consisted of 5 rows of 10 seats each. and there were 24 students (16male. 8 female). The students were initrurtrd to m w e t o m e side of the room and to spread out nlmg the w~II.Theywere told tuohry a short set ul rule*. which were llited on the rhnlkhonrd to p r w m t them from forgetting. The rules were: 11 More to the wpusite side of the r w m almg the nearest row 2) Move a t an easy pace 3) Sit down in any unoccupied chair 4) Women: sit for 3 seconds 5) Men: sit far 6 seconds 6 ) Don't he oolite Rule 2 is intended to orevent a mad race across the room from nccorrine. Rules the retentinn n--r o r e w -~~~ ~~~" ~ .. ..3. t.o .5 .renre4ent ..r...................... in w h ~ r hwomen are less s t n m ~ l yremined than men. Rule 6 prevent* a confounding srlection procesc from wvurring, namely men allow~ngwomen to move ahead r,i rhem out of rourtrsy. Molecul~.rdon't follow rules utrtiqurtre. When enumerated, each rule was described to ensure it was undemtoad properly. In particular, to measure time accurately the students were instructed to count to themselves "one one-thousand, two one-thousand, On my signal, the students began moving through the chairs. I had t o remind them once to adhere to the rules and t o keep going. I called a halt when all of the women had reached the opposite wall. Then I told them to observe that a separation between women and men had been cleanly achieved. Immediately, 1reinfored what had happened using the proper chemical ex~lanationof two molecules with differing nhnae. ..deerees of interaction with a stationarv ~, Theewnt wns highly swceaslul. T h e s t u d m ~ ~ e n p s ethechangr d ofpare, and thecnt~repnredure ux,k only tiw minuter tu acnxnplish. Since !no knwlcdye d r h e m ~ r t r yIS rrquirrd for pfrfc.rmance, the approach is applwahle to any type d student. Adaptation to different classrooms should be easy. For instance, in a large lecture room an aisle could be used as the column and the stair-steps as the "dates": a portion of the class could be selected for ~ a r t i c i ~ a t i o n , After this strsim, my studrnts how been asking when the next "partiripaton chemi5tryWexperiment would be. so theapproachseems to how made asdid imprerswn. I rerommrnd "classroom rhromatqyraphy"a$a worthwhile injtructimal tool. I'erhaps other aspects ot chemiitry c d d he nnthn,pornorphized u irh similar jucrrss ~
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Christopher F. Bauer University of New Hampshire Durham. NH 03824
846
Journal of Chemical Education
I
