Second Grade - November 3rd - 7th, 2008

Our second graders are working on adding three numbers at a time. They will explore the idea of whether order matters when adding a group of numbers. When adding 2 + 3 + 5, does it matter if we add 2 + 3 first? 2 + 5? 3 + 5? As students discover that order does not matter, they are really investigating the associative property of addition. a + (b + c) = (a + b) + c.

Students are also reviewing their doubles - 2 + 2, 3 + 3, 4 + 4, etc. Students use this knowledge to determine the near-doubles. 2 + 3, 3 + 4, 4 + 5, etc. Students should notice that the answer is just one more than the answer to the doubles combination.

By this point in the year, second graders should be fluent (not necessarily instantaneous recall) with the following combinations: plus 1 (4 + 1), plus 2 (4 + 2), combinations that make 10 (7 + 3), and doubles (6 + 6).