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Peabody TeachFor teachers and grown-ups

Number line

Type a sum and a little hopper hops it along the line, in tens then ones or bridging 10, while the equation builds. Play Where's the flag? in teams, draw on the line, hide parts under cover cards, and print worksheets with an answer page. Whole numbers, negatives, fractions and decimals.

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Tap the line to place a marker. Drag a marker to move it. Tap a marker’s mark again to remove it.
Type a sum, watch it hop

Hop the tens one at a time, then the ones in one hop. On fractions and decimals: wholes, then the part.

The line
Markers and jumps
View

Drag the empty line to move it when zoomed. Ctrl and scroll also zooms.

Print

Lines with the numbers you choose, for any task. The sheet uses the line above.

Keys: Enter hops a typed sum, Space hops once (or reveals the flag), P plays all, S sound, G Where’s the flag?, D pen, V cover card, arrows move a selected marker or card, Delete removes it, + and − zoom, H hides numbers, R resets, F full screen, Esc closes.

How to use it

  1. Type a sum such as 37 + 25, 62 − 25, −4 − (−3) or 3/4 + 1/2 and press Enter. If it does not fit the line on screen, the tool picks a line that does.
  2. Choose how to split the jump (tens then ones, bridge 10, by ones or one jump), then press Space for one hop at a time or P to play them all. Turn on Sound (S) to hear each landing.
  3. Tap the line to place markers, or press G for Where's the flag?, D for the pen and V for a cover card. Under Print, pick blank lines or a worksheet with its answer page.

Ideas for class

  • Type 37 + 25 with Tens then ones, then again with Bridge 10, and ask the class which way they would do it in their heads.
  • Turn on Sound and type 0 + 20 with By ones: counting on is a rising tune. Then type 20 − 20 and hear it fall back to the low home note at zero.
  • On a −10 to 10 line, type 3 − 5. The hopper stops at zero on the way through, and the notes turn minor below zero.
  • Play Where's the flag? on a 0 to 100 line: the numbers vanish, each team places its pin for the number on the board, and Reveal raises the flag and shows who was closest.
  • Switch the game to Higher or lower and ask the class for the guess that rules out the most of the line. Halving finds any number from 0 to 100 in seven guesses.
  • Put a cover card over the answer of a hopped sum, ask for a prediction, then tap the card to lift it.
  • Use the pen to circle the bridge to the next ten, or to write the missing jump on an open stretch of line.
  • Print a Jump equations sheet for homework and keep the answer page. The sheet number at the top prints the same questions again next year.
  • Put a marker on 3/4 on a line cut into fourths, then change the line to eighths and see that the same spot is labelled 6/8.
  • Zoom in on the space between 0.4 and 0.5 on a line of hundredths to show there are more numbers there than students expect.

Related

Questions

What sums can I type?

Adding or subtracting two numbers: whole numbers (37 + 25), negatives (−4 − (−3) or −4 − −3), fractions (3/4 + 1/2, 1 1/2 − 3/4) and decimals (0.3 + 0.5, 2.75 − 0.5). Fractions work up to twelfths and decimals to hundredths. If the sum does not fit the line on screen, the tool picks a line that does and keeps your choice of strategy.

What are the ways to split a jump?

Tens then ones hops each ten, then the ones in one hop (37, 47, 57, 62). Bridge 10 hops to the next ten first, then all the tens, then the rest (37, 40, 60, 62). By ones hops one mark at a time for small jumps, and One jump does it in one. On fraction and decimal lines a whole number plays the part of the ten. A jump that crosses zero always stops at zero.

Does the number line make sound?

Only when you turn it on with Sound (S); the choice is remembered in this browser. Each landing plays a note: zero is a soft low home note, positive numbers climb a major scale and negative numbers fall down a minor one, so counting on sounds like a rising tune. Everything you hear is also drawn and written, and nothing is downloaded.

How does Where's the flag? work?

In Teams estimate the numbers on the line are hidden except the ends. The board asks where a number is, two to four colour teams (Blue, Orange, Green, Pink, each with its own shape) place a pin in turn, and Reveal raises the flag, shows every team's distance and gives the closest a point. In Higher or lower the number is secret; each tap is a guess and the ruled-out part of the line turns grey. You can also bury the flag yourself.

What worksheets can I print?

Blank lines (as many as 12 per page, with all, end-only or no labels, or open lines), Place the number, Missing numbers and Jump equations. The three worksheets print with an answer page, use the line you set up, and carry a four-digit sheet number so you can print the same questions again.

Can students use it by keyboard?

Yes. Tab to a marker or a cover card, then use the arrow keys to move it, Delete to remove it, and Enter to reveal or lift it. Enter hops a typed sum, Space takes one hop (or reveals the flag), P plays all the hops, + and − zoom, H hides the numbers, R resets and F goes full screen.

Can it show negative numbers and fractions?

Yes. Set From to a negative number for a line such as −10 to 10, with a proper minus sign. Choose Fractions to split each whole into halves up to twelfths, with labels in lowest terms (the second eighth reads 1/4), and turn on Mixed numbers to see 1 1/2 instead of 3/2. Decimals go to tenths, quarters, halves, twentieths or hundredths.

Does it store anything about my students?

No. Team points, pins, drawings and covers stay on the screen and are gone when you reset or leave. Your line settings are remembered in this browser, and the Share button puts them in the link after the # sign, which our servers never see.

Nothing you do here is sent to us. Names, lists and settings stay in this browser. No sign-in, no ads.

Using a number line in class

A number line is the first place students see that numbers have an order and a distance between them. Unlike a counting chart, the gap between 3 and 4 is the same size as the gap between 4 and 5, which is what makes it the right model for measurement, for negative numbers and for fractions as numbers (not just as pieces of a pie).

A sequence that works

  1. Locate. Place a number on a 0 to 10 line. Students say what comes just before and after it.
  2. Jump. Model addition and subtraction as jumps. Name the jump out loud (“plus three”) before you draw it.
  3. Extend. Move to a 0 to 100 line by tens, then to negatives, then to fractions and decimals on a 0 to 1 line.
  4. Estimate. Hide the numbers and ask where 37 belongs on a 0 to 100 line before you reveal it, or play Where’s the flag? in teams so every pin is a committed guess.

Hops that match the way children think

Children who add 37 + 25 in their heads rarely count on by ones. Most hop the tens first (47, 57, then 62) or make a friendly number first (37 to 40, then 60, then 62). Type the same sum with Tens then ones and with Bridge 10 and put the two pictures side by side in a discussion: both are right, and the line shows why. Subtraction works the same way backwards, and a jump through zero always stops at zero so students see the sign change.

What to watch for

  • Students who count the marks instead of the gaps: they say 0 to 5 is six jumps. Draw the jumps to show it is five.
  • Fractions placed by the size of the denominator (1/8 further than 1/4): put both markers on the same line.
  • Decimals treated as whole numbers: 0.3 versus 0.30 versus 0.03 are easy to see on a line of hundredths.