Lengths on a Number Line

Show length sums and differences as jumps on a number line.

Warm-up, learn, try it together, practice, then a quick check. About 15 minutes.

What children learn in Level 43

A number line is like a long ruler. Each space is 1 unit, like 1 inch.
A worm crawls 8 inches, then 5 more inches. Start at 0, hop 8, then hop 5. It lands on 13. 8 plus 5 is 13 inches!
Your turn! A ribbon is 15 inches long. We cut off 6 inches. Start at 15 and tap where you land after hopping back 6.
15 minus 6 is 9. There are 9 inches of ribbon left.
For longer lengths, the number line can count by 5s. A 20-foot fence, plus 15 more feet, is 35 feet!

Georgia's K-12 Mathematics Standards:

2.MDR.5.5 — Represent whole-number sums and differences within a standard unit of measurement on a number line diagram.