This Fluency Activity is a part of the Lesson 6, Unit 3, Grade 1. This fluency activity reviews the grade level standard of understanding subtraction as an unknown addend problem and prepares students for compare with difference unknown problem types in this lesson. In Cold Call, the teacher asks a question, pauses to provide think time, and then randomly calls on a student or group of students to answer. This game helps motivate all students to mentally solve the problem so they are ready if they are chosen to answer.