Hundreds chart

A 1 to 100 chart (or 0 to 99, or 1 to 120) you can colour, cover and count along on the projector, with missing-numbers puzzles and printable versions.

How to use it

Tap a number to colour it. Pick one of four colours, or switch to Cover to hide numbers and ask the class what is underneath.
Choose a number under Count by to light up its multiples. Turn on One at a time and press Next so the class counts aloud as each square lights.
Press Make a puzzle for a missing-numbers sheet, or choose a version under Print (full, blank, puzzle with answer key, or as coloured) and press Print this version.

Ideas for class

Count by 10s and ask what stays the same in the colored squares: the ones digit never changes.
Cover five numbers and have students write what is under each cover, then lift the covers to check.
Colour all the multiples of 2 yellow and all the multiples of 5 blue, then ask which squares are both. Those are the multiples of 10.
Start at 34 and give directions: down one, right two, up one. Students say where they land and how the number changed.
Count by 9 with One at a time. Students notice the squares form a diagonal and explain why with “add 10, take away 1”.
Print the blank chart for students to complete, then compare with the full chart for self-checking.
Print three different missing-numbers puzzles at Easy, Medium and Hard for a centre. Each has a puzzle number so you can reprint it, and an answer key page.
Use the 0 to 99 chart to show that each row is a “decade” (0 to 9, 10 to 19) and the 1 to 120 chart for the numbers past 100.

Questions

Which chart should I use: 1–100, 0–99 or 1–120?

Use 1 to 100 for the usual chart. Use 0 to 99 when you want each row to be a decade (all the numbers with the same tens digit in one row) and when students are learning that zero is a number. Use 1 to 120 when your standards ask students to count and work with numbers to 120, as many first grade standards do.

How do missing-numbers puzzles work?

The tool picks the hidden numbers from a puzzle number, so the same number always gives the same puzzle. Easy puzzles never hide two touching numbers, so each missing number has a neighbour to count from. Medium never hides two numbers side by side in a row. Hard can hide any numbers. The printed answer key marks every number that was missing.

Can I print a puzzle for each student that is different?

Yes. Press New puzzle to get a different puzzle number, set Print to Missing numbers puzzle, and print. Do it again for another. The puzzle number is printed at the foot of the page so you can match keys to sheets.

Why does the chart start at 1 and not 0?

Most US classroom hundreds charts start at 1, so the last column ends in a multiple of 10 (10, 20, 30 …). The 0 to 99 version is offered because it makes the tens digit constant across each row.

Does it save what I colour?

No. Colours and covers clear when you leave the page. Your choice of chart and print settings are remembered in this browser only, and Share copies a link with those settings after the # sign, which our servers never see.

Can students use it on their own tablets?

Yes, every square is a button, and the arrow keys move between squares. It also works with no internet connection once the page has loaded.

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Teaching with a hundreds chart

The hundreds chart turns the base-ten system into something students can see. Because every row has ten numbers, moving down a row always adds 10, so a student who can find 34 can find 44, 54 and 64 by looking down. That is the reason it appears in so many first and second grade lessons on place value, skip counting and mental addition.

Patterns to point out

Going down one row adds 10: 34 → 44 → 54. Going up takes away 10.
Going one square to the right adds 1; one to the left takes away 1.
Every number in a column ends in the same digit: the whole column under 7 ends in 7.
Counting by 10s lights up one column; counting by 5s lights up two (the 5s and 0s).
Counting by 2s makes stripes: every other column is highlighted, all the even numbers.
Counting by 9s runs diagonally down and to the left, because adding 9 is adding 10 and taking away 1.
Counting by 11s runs diagonally down and to the right, because adding 11 is adding 10 and 1.

From counting to computing

Start with counting on the chart, then ask students to add 10 or subtract 10 without counting each square. Next, add 9 and 11 by moving diagonally. Later, let students solve 47 + 23 by moving down two rows and right three squares. The chart should become unnecessary: when students stop looking at it to find the answer, take it away.

When to cover numbers

Covering numbers shifts students from reading the chart to using the structure of it. Cover a single square and ask how they know which number is there. Cover a whole row and ask what could be in the middle. Missing-numbers puzzles at the Hard level are a good quick check of number sense after a unit.