Doubles Plus One Activity and Math Center: Type FREE for code at checkout. This Smart Notebook file includes an activity for second grade to reinforce math skills in Operation and Algebraic Thinking Core Standard 2.2. This activity helps students to use the double plus one strategy to solve addition problems. The Smartboard lesson can be used as a two player center or two team whole group activity. This file includes: objectives, core content standards, a quick review of the double plus one strategy, and directions. I hope you and your students enjoy this Activity from Smartboardattendance.com