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Grade 2 Math · World 3: Hundred Harbor · Level 26
Hop on the Number Line
Add with jumps of tens and ones on an open number line.
Warm-up, learn, try it together, practice, then a quick check. About 15 minutes.
What children learn in Level 26
- An open number line has no numbers until you need them. Let's add 34 plus 25. Start at 34.
- 25 is 2 tens and 5 ones. Hop 10 to 44, then 10 more to 54.
- Then hop the 5 ones, from 54 to 59. So 34 plus 25 is 59!
- You can make bigger hops too: plus 20 in one hop, then plus 5.
- For 47 plus 28, hop 3 to get to the friendly 50. Then hop 20 to 70, and 5 more to 75.
Georgia's K-12 Mathematics Standards:
- 2.NR.2.4 — Fluently add and subtract within 100 using strategies based on place value, properties of operations, and/or the relationship between addition and subtraction.
- 2.MDR.5.5 — Represent whole-number sums and differences within a standard unit of measurement on a number line diagram.