Look For and Express Regularity in Repeated Reasoning.
1st Grade

Mathematically proficient students in First Grade begin to look for regularity in problem structures when solving mathematical 
tasks.

•  For example, when adding three one-digit numbers and by making tens or using doubles, students engage in future tasks looking for opportunities to employ those same strategies. 
• Thus, when solving 8+7+2, a student may say, “I know that 8 and 2 equal 10 and then I add 7 more. That makes 17. It helps to see if I can make a 10 out of 2 numbers when I start.” 
• Further, students use repeated reasoning while solving a task with multiple correct answers. For example, in the task “There are 12 crayons in the box. Some are red and some are blue. How many of each could there be?” First Grade students realize that the 12 crayons could include 6 of each color (6+6 = 12), 7 of one color and 5 of another (7+5 = 12), etc. In essence, students repeatedly find numbers that add up to 12.