Keener is a Canadian slang term used to describe someone who is overly eager to learn and prove themselves. Can sometimes be considered to describe a suck up too. Simply words are nerd, geek, smartypants, etc. The only difference is that there is less emphasis on social standing and natural ability. Also, the word puts more emphasis on enthusiasm, willingness, and over all attitude.
A: Cindy is such a keener, she raised her hand for every question in Mr. Willison's class.
B: I know, she gets an A on every single test, and she freaks out when she doesn't.