Four Squares are great for students to work with new vocabulary words. I use these to support the learning of my readers because in order for a student to own a word, they have to do more than just copy a definition.
I encourage students to write the word in a memorable way (fancy styled writing, color, write really big letters, etc) to help kick off a visual association with the word. My students use these as extra homework to earn homework saves. It is an extrinsic motivator but it's also helping them develop their vocabulary ;-)