In this chapter, students should remember how to regroup/borrow from the digits in the hundreds and tens places, in order to find the difference (-). Students will practice using base 10 pictures, using number lines, and breaking apart numbers in order to subtract. Students will model subtraction by breaking apart one hundred into ten tens and breaking apart a ten into ten ones. They will first model subtraction with pictures, and then transition to solely using digits. Subtraction will be practiced with and without regrouping to find the difference. Students will also use the missing addend to find the difference, as well as a whole minus a part equals a part. Students will finish off the chapter by writing subtraction equations with a missing part. Multi-step problems will also be solved using the whole-part-part method and bar models.