This Fluency Activity is a part of the Lesson 21, Unit 7, Grade 2. Give students a base number such as 9. They roll their die to find the "rule." For example, if they roll a 5, they add 5 repeatedly: 9 + 5 = 14, 14 + 5 = 19, 19 + 5 = 24. Students track their number sentences in their notebooks and count the total of number sentences they have written after 30 seconds. Continue the process with a different base number and/or operation.