This Fluency Activity is a part of the Lesson 1, Unit 7, Grade 2. During Topic A and for the remainder of the year, each day's Fluency Practice includes an opportunity for review and mastery of the sums and differences with totals through 20 by means of the Core Fluency Practice Sets or Sprints. Five options are provided in this lesson for the Core Fluency Practice Set, with Sheet A being the most simple to Sheet E being the most complex. Start all students on Sheet A. Students complete as many problems as they can in 120 seconds. The recommended goal is 100% accuracy and completion before moving to the next level.