"Back to school" as an adjective or noun

What would be a good noun to call a person who deliberately, willfully makes a "back to school" trip to get a refresher on a subject (like geometry, calculus, biology)? Humorous nouns and expressions accepted.

Examples of intended usage:

• I am a … in calculus.
• She has been a … in biology recently – she decided she needed a refresher in animals taxonomy.

A late student would sound a bit like an obituary. Not sure.

Not even sure I phrased my question correctly – "back to school" is a difficult idea to convey within a sentence.