Friendly numbers (43 + 27 add tens, then ones) Moving 27 to 30, adding on. Relating compensation strategies to the number line. (43 + 27 = 43 + 20 + 7 or 43 + 27 = 43 + 7 + 20) Addition in any order, compensation, decomposition of numbers
, Numberline Age Talk, Nine grows to 10. Place a seven year old on the number line and an older sibling on 12. Discuss the difference in ages. Ask how old will you be next year? Your sibling? What is the difference in ages? When you are nine, how old? When sibling 15 how old will you be? When you are 9 how old sibling? Ten? How does knowing about the number line and ages help me change 17-9 to an easier problem? Can we apply this idea to 21-8? 42-17?