In this math lesson, the teacher introduced students to a technique for tackling addition and subtraction problems using multiples of ten, emphasizing the “9 rule” and “hop back” method. Students were guided through exercises to practice adding and subtracting single and three-digit numbers, aided by tools like number grids and lollipop sticks. The lesson focused on building students’ ability to adjust their calculations by strategically using and subtracting multiples of ten.