Smart Rats<br>When I was in high school I took biology. The classroom was in a lab, with rats and frogs, The rats ran on the wheel, which squeaked. The teach put a pencil in to stop the wheel from working. The room cheered when the rats pushed the pencil out and ran.
biology can used rats to show students how to deal with them. 
according to the text, the rats ran on the wheel, which squeaked, so we don't know if they are used to teach them how to deal with them, but it could be the reason. 
( z1 possible :ARG1 ( z2 use :ARG0 ( z3 biology ) :ARG1 ( z4 rat ) :ARG2 ( z5 show :ARG0 z3 :ARG1 ( z6 thing :manner-of ( z7 deal :ARG0 ( z8 person :ARG0-of ( z9 study ) ) :ARG2 z4 ) ) :ARG2 z8 ) ) )