A warm-up is a short activity at the start of a lesson to jump-start students' thinking. Warm-ups have many purposes including: to introduce a new topic to reinforce skills to motivate students to prepare students to learn to assess how much students know The following warm-up is a magic square for students who have mastered math addition facts and need a challenge. A magic square is a matrix in which the numbers in every row, column, and diagonal add up to the same number. In this magic...