This Fluency Activity is a part of the Lesson 14, Unit 5, Grade 2. During Topic C and for the remainder of the year, each day's fluency activity 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 Set A being the most simple addition fluency exercise of the grade to Set E being the most complex. Start all students on Set A. Keep a record of student progress so students can progress to more complex sets when they are ready. Students complete as many problems as they can in 120 seconds.