Divide Using Mental Math
Mr. Moreno wrote this problem on the board. “What is a story that might make sense for this problem?” he asked.
“How about Girls Lacrosse?” said Jessie. “If there are 1140 total players and there are 12 players on a team, how many teams would you have?”
“That sounds good. Let's first write this division problem as a multiplication problem.” Mr. Moreno wrote this on the board.
12 ? = 1140
“Sometimes it is helpful to write number sentences we know to help us solve division problems.” Mr. Moreno wrote some number sentences on the board.
12 10 = 120
12 100 = 1200
12 50 = 600
12 40 = 480
60 ÷ 5 = 12
“Which of these might be helpful for solving the problem?” asked Mr. Moreno.
“I would use 12 50 = 600, 12 40 = 480, and 60 ÷ 12 = 5,” said John.
“I would use 12 100 = 1200 and 60 ÷ 12 = 5,” said Michael. Both John and Michael shared their reasoning.
