Same Math › Grades 1–3 › Open number line
What is an open number line?
An open number line is a plain line with no numbers printed on it. Kids mark where they start and draw jumps to add or subtract, so you can see exactly how they worked it out.
- Mark where you start: 47. Nothing before it matters.
- Jump the tens, then the ones: +20, then +5.
- Where you land is the answer: 47 + 25 = 72
Why schools teach it
It shows the math kids do in their heads
Second graders are expected to add and subtract within 100 using strategies based on place value (2.NBT.B.5) and to work with number line diagrams (2.MD.B.6). The open line puts those strategies on paper, so the teacher (and you) can see each step.
It's especially good for subtraction. Instead of taking away and "borrowing," kids can count up from the smaller number to the bigger one and add up the jumps.
At the kitchen table
What to say, and what to skip
Say this
Where do you start?
Can you jump by tens first?
Is there a friendlier number to jump to?
From 47, jumping +3 to land on 50 is a smart move.Can you count up from the small number to subtract?
62 − 38 is the distance from 38 to 62.
Skip this
- Drawing every tick from 0 to 100.The open line only marks the numbers you land on.
Just line them up and carry.
That's the stacked method, which comes later.- Insisting on one right way to jump.47 + 25 can be +20 then +5, or +3 then +22. Both are correct.
See it in action
Solving 62 − 38 by counting up
Start at 38 and jump to the next ten
38 + 2 = 40Jump by tens as far as you can
40 + 20 = 60Jump the rest, then add the jumps
60 + 2 = 62, so 2 + 20 + 2 = 24
No borrowing needed. The jumps are the answer.
Free practice sheet
Make an open number line sheet
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Parents also ask
How is this different from the number line I learned?
The old one had every number printed. The open line is blank, so kids decide where to jump and how big.
Do the jumps have to be to scale?
No. Bigger jumps should look a bit bigger, but nobody measures.
Why does my child jump to 50 first?
Landing on a ten makes the next jump easier. It's a strategy teachers encourage.
When do kids stop drawing it?
Usually in 3rd grade, as the jumps move into their heads and the stacked method arrives.