I was able to quickly and efficiently get the best thesis statement from each of my two AP US History classes. We write individual thesis statements, then group, then whole class, then reflect/analyze the best written statements.

1. I project an essay prompt on the LCD. Each student writes a thesis statement. 
2. Students are placed in groups to choose the best thesis statement in their group, revise, and then to scribe that revised thesis statement into a Google Doc. I then have 4-5 of the best thesis statements in each class.
3. Each class votes on the best thesis statement from the other class to mitigate home bias.
4. The next day we had a whole class discussion in each class on why the students voted for those particular thesis statements.