WordPress.com



2nd grade Number TalksStrategies for AdditionCounting All/Counting On: This is an entry-level strategy. Since we want students to move toward a more efficient method for adding, we honor thinking from students but always make a connection to a more efficient strategy.DoublesNear DoublesMaking TensLandmark or Friendly NumbersBreaking Each Number into Place Value Example: 24 + 21 can be seen as 20 + 20 + 4 + 1Compensation When students understand that you can compensate in addition (remove a specific quantity from one addend and add the same to another addend) without altering the sum, they can begin to construct powerful mental computation strategies from this concept. Composing and decomposing numbers is key to this strategy. Example: 5 + 9 can be seen as 4 + 10 or 19 + 6 can be seen as 20 +5Adding up in Chunks We want students to be able to add multiples of ten to any number with ease. Adding up in chunks builds on this idea by encouraging students to keep on number whole while adding chucks of the second addend. Tools to use: Open Number line or 99 Chart; Example: 28 + 24 is 28 + 20 to get 48; then 4 can be broken into 2 and 2 (friendly number) so 48 + 2 = 50 + 2 = 52Strategies for SubtractionAdding Up – Allows student to build on their strength with addition. The larger the jump, the more efficient the strategy will be. 15 – 9 can be seen as 1 more to get 10; 5 more to get 15 for a total of 6. 23 – 19 can be seen as 1 more to 20 and 3 more to 23 for total of 4.Removal: Most students will gravitate to this strategy since we have taught the algorithm. However, we would like for them to start counting back by numbers other than 1. For instance: For 21-9, decompose the 9 to 1 and 8. Then 21 – 1 to 20 and 20 – 8 is 12 ................
................

In order to avoid copyright disputes, this page is only a partial summary.

Google Online Preview   Download