This activity is part of my unit on getting students to think flexibly about addition in subtraction.
I use it with 3rd grade as a review of what their 2nd grade teacher should have introduced them to. It would also work well for students in 4th having difficulty with the standard algorithm.
Here is the 3rd grade standard...
3.NBT.2 Fluently add and subtract within 1000 using strategies and algorithms based on place value, properties of operations, and/or the relationship between addition and subtraction.
Here is the 2nd grade standard...
2.NBT.B.7 Add and subtract within 1000, using concrete models or drawings and strategies based on place value, properties of operations, and/or the relationship between addition and subtraction; relate the strategy to a written method. Understand that in adding or subtracting three-digit numbers, one adds or subtracts hundreds and hundreds, tens and tens, ones and ones; and sometimes it is necessary to compose or decompose tens or hundreds.