The first graders in Mr. Ridgley’s class are working on adding sums up to 20. During math time, he invites three children to gather around a gameboard and introduces two, 10-sided dice that look like jewels. “The purpose of our game today is to roll the dice and find the sum of the two numbers,” he says. “You’ll find the number representing your sum on the gameboard and place your chip on the numeral. When you have three chips in a row, you’ll have completed the round.”  

Mr. Ridgley’s plan is to support children’s addition fluency and note the strategies they use, which meet his state’s math standard of using “mental strategies flexibly and efficiently to develop fluency in addition and subtraction within 20” (Tennessee State Board of Education 2021, 3). 

One of the children, Angelo, races over to the board. Last year, Angelo struggled with math and was often overwhelmed by the worksheets he had to complete. Now, though, he happily plays with the other children as they take turns rolling the dice and adding to 20.  

Angelo rolls a 5 and a 4. “Five,” he says, placing his finger on the 5 die. He then uses a counting-on strategy to arrive at the sum. “6, 7, 8, 9. The answer is 9!”  

“You also know the double strategy,” Mr. Ridgley reminds him.  

“Oh yeah,” Angelo says. “I know 4 plus 4 is 8, and one more makes 9. I learned that in kindergarten.” Mr. Ridgley then asks, “Could 5 plus 5 help you solve 5 plus 4?”