Five pages of strategies for adding two two-digit numbers, the heart of 2nd grade addition. Page 1 adds by place value with no new ten: the tens together, the ones together, then the two parts (43 + 25 is 60 + 8, 68). Page 2 shows both numbers in base-ten blocks; students count all the tens and ones (5 tens 13 ones), trade 10 ones for a ten (6 tens 3 ones) and write the sum. Page 3 uses an open number line: start at the first number, jump by tens, then jump the ones in one jump (46 + 27: 56, 66, 73). Page 4 makes a ten first by moving a few from the second number to the first (38 + 25: 38 + 2 = 40, so 40 + 23 = 63). Page 5 asks for any strategy with the work shown, then shows two animals with different answers, one with a common mistake (forgetting the new ten, writing 7 tens 14 ones as 714, or adding the tens as ones); students circle who is right and show how they know. Each page starts with a worked example.
Before page 2, build 38 and 25 with base-ten blocks and push the ones together. Ask what to do with 13 ones before anyone writes, then trade 10 of them for a rod. For page 3, draw one open number line on the board and let students tell you where to jump: there is no single right picture, only jumps that add up. Page 5 makes a good talk: read the animals' answers aloud and let partners argue which one is right before they write.
Ask questions like "You have 38 stickers and get 25 more. How many now?" and ask how your child got the answer. Dimes and pennies work well: 3 dimes 8 pennies and 2 dimes 5 pennies, then trade 10 pennies for a dime.
This pack supports the following Common Core State Standards for Mathematics:
© Copyright 2010. National Governors Association Center for Best Practices and Council of Chief State School Officers. All rights reserved.
A 5-page 2nd grade pack for adding two two-digit numbers with place value strategies. Add the tens, add the ones and put them together (43 + 25 = 60 + 8), then count two numbers in base-ten blocks and trade 10 ones for a new ten. Jump by tens and then the ones on an open number line (46 + 27: 56, 66, 73), and make a ten first by moving some from the second number (38 + 25 = 40 + 23). Last, add any way you like and show your work, then decide which animal is right and show how you know. Every page comes in color and in black and white. Answer keys included.
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