Multiplication and Division Facts to 100
Warm-up
Doubling chain: 3x2=6, 6x2=12, 12x2=24, 24x2=48. Each step doubles. Now: what is 6x4? (6x2x2 = 12x2 = 24.) 6x8? (6x2x2x2 = 48.) This shows that all powers-of-2 multiplications can be computed by repeated doubling from a known fact.
Explore
Array game: player 1 rolls two dice to get factors (e.g., 6 and 7). They colour a 6x7 array on grid paper and record the product. Player 2 does the same. After 5 rounds, each player calculates their total area. Highest total wins. Strategy: which arrays give the most product? This embeds multiplication in spatial and quantitative reasoning.
Consolidate
Practice
Students play the array game for 10 rounds, record all products, and list the four fact-family members for 6 of the products. Exit ticket: use the doubling strategy to find 4x8.
Exit ticket
Students play the array game for 10 rounds, record all products, and list the four fact-family members for 6 of the products. Exit ticket: use the doubling strategy to find 4x8.
8x5 = (8x10)/2. 8x10=80. Half of 80 = 40. So 8x5=40. Alternatively: 5x8 = skip-count by 5 eight times: 5, 10, 15, 20, 25, 30, 35, 40. Same answer.
6x9=54 (commutativity), 54/9=6 (inverse), 54/6=9 (inverse). You can also derive: 8x6 = 9x6 - 6 = 54 - 6 = 48. Near-fact reasoning gives extra mileage.