In his sophomore year, his grades plummeted and was declared academically ineligible.

Laura's grades plummeted, prompting her parents to pull back on their hours somewhat.

Kim's good grades in school plummeted.

He dabbled in drugs, mainly marijuana, and his grades and behavior plummeted.

James's grades plummeted, and his feelings about school crashed with them.

His grades plummet, he gets into fights often, and even gets sent to Juvenile Delinquency.

She started having problems with her friendships and her grades plummeted.

His grades in math plummeted to 65 from 90 the year before, and his grades in other subjects were worse.

Her father felt rejected and angry, and the tension showed at school, where her grades plummeted.

He stopped paying attention in class and his grades plummeted.