This is a three week unit to teach Second Grade Common Core Standard 2.NBT.5. This unit focuses on teaching several different subtraction strategies to solve subtraction problems. Students will use a 100's board to solve subtraction problems, the Break Apart or Decomposing Strategy, Using "Friendly Numbers", subtracting tens and ones without regrouping, Using a Number Line, and Using Addition to check Subtraction. This unit includes everything you need to teach this standard for subtraction, in