The most effective rebuttal to the counterclaim is:
"Longer school days lead to a decrease in crime committed by teenagers, since students have less free time."
This rebuttal directly addresses the concern raised in the counterclaim regarding the potential loss of time for socializing and other enriching activities. By highlighting that extended school days can lead to a positive outcome, such as reduced crime, it reinforces the argument that longer school days can have broader societal benefits, which may outweigh the drawbacks articulated in the counterclaim.