But it isn’t enough to understand what addition and subtraction mean and how they can be
applied to solve word problems. Students in Grade 2 must also learn general and efficient
methods for expressing the sum or difference of two multi-digit numbers as another multi-digit
number (working within 1,000 at this grade; note that fluency is expected within 100, and
single-digit sums must be known from memory by year’s end).
How would you count the marbles in this box? Would you count one by one? How about grouping by tens? When you teach place value, all of these questions come to mind. I highly recommend this article from EngageNY. It would be great to share with fellow educators and parents. Terrific explanation of what needs to happen with students who are learning about ones, tens, and hundreds.