This is a strategy I just recently read about and shared at the Middle School Curriculum Meeting. I really like it because it gives the teacher a good pulse on the students' understanding of a concept and lets you know whether or not reteaching is needed for part, or all, of what your objective was. It is called "whip around" because it takes only a little bit of time to "whip around the room," but it also can "whip around" your instructional plan into the right direction.
I read about this as a closure activity, but I think you can use it at any point you want to stop and check for understanding. Write down the main points that you want your students to grasp. Ask them a probing question, such as, "Write three of the most important things to remember about the beginning of World War I" Have them jot their answers on a scrap piece of paper and then stand. Go around the room having the students read their three to five points and as they listen to one another, if they have the same thing written (exactly. . .so you can hear slight variations) then they can check that off their list. Go around the room until everyone has read all of their answers.
As they read their answers, tally mark next to the points that you wanted them to grasp. Look for patterns. Students will avoid points that they don't understand well, or they will give you misinformation that needs correcting. This takes only a few minutes and gives you and the students immediate feedback on what they are really taking away from the learning. You may close the class knowing exactly what review point you will begin with the next day.
Check out Checking for Understanding by Douglas Fisher and Nancy Frey