I can't figure out how a teacher could do this, but the classroom climate could change....why does group b, c, and d know that group a finished first...there is no finish line...I would work from that end....group a shouldn't yell "done!" Group c shouldn't be looking over group a's shoulders to see if they are done and then shouting...look they are done!

...reading is pleasure, not just something teachers make you do in school.~B. Cleary