A friend is taking a class in childhood education. " Back in the old days," she says, " teachers used physical punishment, but of course that's not allowed any more.

Now a good teacher should only use reinforcement. When children behave, teachers should provide positive reinforcement, like praise. When children misbehave, teachers should provide negative reinforcement, like scolding or withholding privileges."

What is your friend misunderstanding about reinforcement? Can you give better examples of how negative reinforcement could be productively applied in an elementary school classroom?