Little House on the Prairie - Season 5 Episode 11 -

Andy Garvey's mother is embarrassed by her son's performance at school. She hires Nellie Oleson to tutor him. Nellie reveals to Andy how she gets such good grades. Nellie makes Andy keep the secret of Nellie cheating. Andy eventually admits what he has been doing and his mother makes sure that Nellie isn't able to cheat on the next test.