Readington Township school officials gave 29 students detention after they used pennies to pay for their $2 lunches.
Superintendent Jorden Schiff said it started out as a prank. But as the eighth-graders began to get in trouble for taking up so much time, it turned into a protest about Thursday's shortened lunch period.
Schiff said the students were punished for holding up their peers and disrespecting lunch aides.
Schiff said some parents think a two-day detention went too far and others think it wasn't enough.
--NBC10 on when legal tender is no longer acceptable currency