In this video, Harley moves in with Harry and makes Harry's life miserable. Harley spies on Harry writing in his diary. When Harley "borrows" the diary, he finds it is written in a code using numbers. Harley figures out a pattern with numbers and letters and decodes the page to find it is a message for Harley saying it is time to move out. In the accompanying classroom activity, students create their own codes and clues using whole numbers and fractions. This resource is part of the Math at the Core: Middle School Collection.