Beat Up Sixth Grader

You choose a creature. If the target is not in sixth grade, nothing happens. If they are, they must make a dexterity or constitution saving throw (Their choice). On a fail, they take 5d8 nonmagical bludgeoning damage and are now targeted. On each of your turns, you can choose to take this action again for them to repeat the saving throw and take damage again, as long as they are within melee range.

At higher levels, the creature takes an additional 1d8 bludgeoning damage for each level above 3rd.