Standard 2.NBT.B.7 even notes that the models or drawings (which I also call models) are separate from the strategies that are based on:Īs you can see, the strategies are clearly outlined in the standards. relationship between addition and subtraction.When looking at the standards above, I can see that the strategies are clearly noted in the standard: Models are how the strategies are organized on paper so that students can explain or see the strategy.
Strategies are usually how students approach and manipulate the numbers. If you are familiar with my Addition & Subtraction Word Problems, you may have noticed that I make a big distinction between the strategies used when solving problems and the models students employ with those strategies.
Read to the end to find out how I address the standard algorithm in our classroom.Īre you interested in a free sampler of some of my Two-Digit Addition and Subtraction Products? Nowhere in those two standards does it say anything about the standard algorithm that we all learned in school (most likely with the language of “carry” and “borrow”), nor is the standard algorithm directly addressed in the Second Grade Common Core Standards. 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. The Common Core Standard for two-digit addition & subtraction is:įluently add and subtract within 100 using strategies based on place value, properties of operations, and/or the relationship between addition and subtraction.Īnd, the standard for three-digit addition and subtraction, to show where we’re headed:Īdd 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.