Extend Addition and Subtraction Within 1000
Moving on to extend addition and subtraction to numbers up to 1000, students will continue the use of word problems, however at this point the base 10 blocks will be fazed out and replaced with the place value cards. Students will use the hundreds rods discussed in the teaching strategies for some concrete models but this will get to be too cumbersome and difficult when we add multiples of hundreds. Using the place value cards will continue to give students an object to hold and manipulate for the concrete and pictorial models. They will lay out the cards and physically rearrange them before they transition back into symbolic.
Because students have mastered the previous 2 digit addition and subtractions skills and have been given adequate time to work within each sub-step I will not repeat those sub-steps. However, we will work with adding just in the hundreds column for a time and then adding work with hundreds, tens and ones independently for a time (no regrouping) before we add the step of regrouping. When we do get to regrouping we will begin with the ones and tens only before moving onto regrouping within all three. This can be extended into 3 rd grade for continued master of hundreds and then into thousands. It continues to be extremely important that students be allowed to thoroughly explore deeply as they move into greater positions of place value. If one small step is missed it leaves room for a week foundation in their understanding.
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