Hilory Paster is a middle school teacher from William H. Lincoln School in Brookline, Massachusetts. She has assigned a problem similar to the one you have just worked on.

In the video segment at left (duration 1:48), you can watch a pair of her students grapple with this problem. As you watch, focus on how Ms. Paster's questions help students with their reasoning. Think about what the fraction pieces add to the lesson.

  Think about reasoning and proof in the context of what you just saw