This activity goes along with the Harcourt math series (2005) Grade 2, Chapter 6, however, the material is just as good to cover the same skill in any series. The level of interactivity depends on the purpose of the activity. For example, in some activities the purpose is to be able to identify the amount rather than create it, so in that case the activity is not interactive. There are, however, many interactive activities. There are generally 30-50 pages in each file. This one focuses on subtraction strategies, including counting back, fact families, relating addition to subtraction, missing addends, and the problem solving strategy write a number sentence.