Spice up your warm-up time by using a "4-Corners" strategy. Using 4 different sets of similar problems, students work individually on a brief set of problems (students don't realize that there are 4 different versions of the problems yet!) Then, after a few minutes of independent work, send students to each of the 4 corners of the classroom according to the small clip art on his or her warm-up sheet to compare and discuss answers. Come back together as a class to discuss solutions and questions. This set of problems helps students practice solving various addition and subtraction problems involving fractions and mixed numbers.