Curriculum

• A flexible cloth or plastic measuring tape marked from 0 to 100, handled by the parent
• Paper
• Pencil

1. Step 1. Point to 0, 1, 2, and 3 on the measuring tape. Notice that adjacent whole-number points are equally spaced and that 3 is three units from zero.
2. Step 2. Ask your child to place 18, 42, and 76 on the line and explain that each position shows that many units from zero.
3. Step 3. Model a paper open number line: label 48 at the start, draw a right-pointing arc labeled +30 to 78, then a right-pointing arc labeled +5 to 83. Explain that the arcs are not drawn to scale; the labels carry the jump values.
4. Step 4. On a second paper line, label 83 at the start, draw a left-pointing arc labeled −30 to 53, then a left-pointing arc labeled −5 to 48. Compare the endpoints and total values with the addition jumps.
5. Quick check. On the 0–100 line, ask your child to place 27, show the addition 42 + 35 with forward tens-and-ones jumps, and show the subtraction 77 − 35 with backward tens-and-ones jumps. Success means the placement is correct and both diagrams land on the correct result.

Worked example. For 48 + 35, begin at 48, move +30 to 78, then +5 to 83. The jumps total 35, so 48 + 35 = 83. Reverse the same length: 83 − 35 uses −30 to 53 and −5 to 48.

Optional challenge. Show the inverse pair 60 + 35 = 95 and 95 − 35 = 60 on the same number line. Explain that both equations use the same 35-unit jump, forward in the addition and backward in the subtraction.

What to notice. Save a photo of the paper showing one placed number, one correct addition diagram, and one correct subtraction diagram, or a short parent note recording all three results and the child’s explanation of forward and backward jumps.