This is a great activity to be used at the beginning of the school year to get students' brains warmed up by having them come up with any topic or math-related word that corresponds to each letter of the alphabet.
For example, students could fill in addition for letter "A" or order of operations for "O."
This is also a good review activity at the end of a unit.
I would reward the first 3 (or so) students who finish with the most words.
Can be edited - if you teach another subject, simply change the word math to the subject you teach.