Or they may take control of the letters and tell the other person to write down all the words that they make. You can assign them 2 different colored pencils for recording if you want to see who is writing what. You can also assign problems from a book and have the kids just take turns writing their answers on a plain sheet of paper. One person chooses a word and calls it from a list. The other one writes it, and the caller checks it.
Students take turns being the caller.
Use Rallytable to fill out a graphic organizer like a story plot map. Rallytable is one of the easiest structures to use in your classroom. It's much easier to get along with just one other person than to have to cooperate with 3 other people. Rallytable saves paper. You only have to run off half as many worksheets.