On a scrap sheet of paper, each student writes down a clue/definition/example for a word on the word wall. The students then ball up their clues and throw them at one another as if they were having a snowball fight. After about 20 seconds of "play time," the students are to pick up a paper ball and return to their seats. (I start counting down when there are 10 seconds remaining.)
When every student is seated again, the teacher selects a student to read the clue from their snowball. The other students are to guess the word on the word wall that corresponds to that clue.