How to use the Hundreds Chart Explorer
A guide for teachers. Students do not need to read any of this — a two-minute demonstration is enough to get them started.
The app does two different jobs:
- Student practice — six activities a child can run independently. The app asks for a prediction before it shows anything, and never rushes them.
- Teacher Mode — an open chart you drive on the board. Nothing is generated, nothing is scored, nothing is timed.
There is nothing to install and no student login. Your choices are saved on the device you are using.
Quick start
- Open the page. You land on the student home screen with six big choices.
- Tap ⚙ Settings once at the start of the year and set the number range and activities you want. Level 1 with the 1–100 chart is a good beginning-of-year setting.
- To teach with it, tap 📚 Teacher Mode. To let students practise, hand them the device on the home screen.
- 🏠 Home in the top bar always returns to the six student choices. ❓ How To reopens this guide.
What is on the screen
- Chart buttons along the top switch between 1–120, the tall 1–500 ⇩ chart, and each hundred up to 901–1000. Only the ranges you allow in Settings appear.
- The 1–500 chart is one long chart that scrolls instead of flipping at each hundred, so a count can run from 88 straight through 98, 108, 118 with every number still on screen. A thick blue line marks the end of each hundred. It follows along on its own as the count moves down.
- The chart is always the biggest thing on the screen. Tapping a square is how students answer most questions.
- The orange ring is the marker. It slides across the chart when a number moves, so the class can watch the jump instead of just seeing the result.
- The panel on the right holds the buttons and questions for whatever is happening. On a tablet or phone it moves underneath the chart.
What the colours mean
A square with a dashed grey outline is a hidden number. Students can still tap it.
The six student activities
🔍 Explore
For: seeing that the chart is built out of tens and ones.
The student taps any number. The app lights up the number before and after it, 10 less and 10 more, and 100 less and 100 more, and writes the facts out underneath. The −100 −10 −1 +1 +10 +100 buttons move the marker; each move produces the equation, the two numbers side by side with the digit that changed in blue (47 → 57), and a sentence about which digit stayed the same. What do you notice? asks a quick multiple-choice question about the last move.
🔢 Count
For: counting sequences within 1,000.
The student chooses to count by 1, 5, 10, 25 or 100, forward or backward, and picks a starting number by tapping the chart or pressing 🎲 Random. Then the app shows 37 → ? and waits — the student taps the next number on the chart. Every number counted so far stays coloured (the newest one in blue, the rest in teal) so the pattern builds up on the chart as they go.
To show what happens crossing a hundred, switch to the 1–500 ⇩ chart before starting. The count runs down one continuous chart — 88, 98, 108, 118 — with the whole trail visible and the chart scrolling to follow, instead of flipping to a new chart at 100. On the single-hundred charts the app still changes chart when a count crosses over, and says so.
The maths rules are built in: counting by 5 starts on a multiple of 5 and goes forward, counting by 25 starts at 0, and counting by 1, 10 or 100 works forward or backward from any number.
🎨 Patterns
For: noticing, extending, describing and creating patterns.
- Continue the Pattern — three numbers are given, the student taps the rest.
- What’s the Rule? — five numbers are shown; the student picks the rule from four choices.
- Pattern Painter — the student taps six to eight numbers in a pattern, then answers a question about the shape it made (“the ones digit stays the same”).
- Make Your Own — the student picks the start, whether to add or take away, and the amount, then builds and predicts their own pattern.
❓ Mystery Number
For: reading the structure of the chart without relying on every label.
- 1. Missing Numbers — several squares are blank. The student taps a number from the list, then taps the square it belongs in.
- 2. Part of a Chart — only a 3×3 piece of the chart is shown, with one number missing.
- 3. Neighbour Numbers — one number sits in the middle and the student fills in the eight around it. Works past 100 too (364 in the middle, 353 to 375 around it).
- 4. Number Clues — either “greater than 40, less than 50, has 7 ones”, or movement clues (“start at 36, move down 2 rows, move right 3”) that finish by showing 36 + 20 + 3 = 59.
➕ Add & Subtract
For: adding and subtracting by decomposing into tens and ones.
A problem such as 38 + 24 appears with the marker on 38. The answer is never shown. The student jumps their own way: six ones and two tens, or two tens then four ones — both are correct. Every jump stays on the chart as a trail (38 → 48 → 58 → 59 → 60 → 61 → 62). Show bigger jumps adds ±20, ±30 and ±50 for students ready to move in larger chunks, and Undo steps back one jump.
When they land, the app writes the equation, the decomposition (24 = 20 + 4), a quicker route if there was one, and how many jumps they used. A longer correct strategy is never marked wrong — it only shows what the shortest path would have been.
⭐ Challenge Me
For: mixed number sense, without being told which strategy to use.
Randomly generated questions: 10 more / 10 less, 100 more / 100 less, the number directly above or below, “start at 28 and add 30”, which number comes next, what is the rule, and find the mistake in a pattern. Students answer by tapping the chart or choosing from four buttons. A small 4 of 10 shows how far along they are. If Random Practice is switched on in Settings, a seventh tile appears on the home screen that pulls from the same mixed pool.
How the app responds — predict, show, notice
The app is built so students cannot press buttons and watch it do the maths for them.
- Predict. Before the marker moves, the student says where it will land.
- Show. The marker slides there and the equation appears.
- Notice. Now and then the app asks a one-tap question about what changed.
When an answer is wrong the app does not reveal the correct one. The first try gets “Try again — what changes when you add 10?”. The second gets a hint (“moving one row down changes the number by 10”). Only after a third attempt does it explain and glow the right square.
If you want a session with no prediction step — free exploring, or a child who needs the support removed — turn off Ask for a prediction in Settings.
Teacher Settings ⚙
Open with the ⚙ Settings button in the top bar. Choices save on that device as soon as you press Save & close.
| Setting | What it does |
|---|---|
| Number range | 1–100, to 200, to 500 or to 1,000. Everything the app generates stays inside this range, and only these chart buttons appear. |
| Offer the 1–120 chart | Adds the 12-row 1–120 chart to the chart buttons. |
| Activities students can use | Tick only the activities you want on the home screen today. Untick the rest so nobody wanders off. |
| Difficulty level | Sets the level, and the lock below makes the level control the range and hidden numbers. See the table below. |
| Add & subtract | Addition only, subtraction only, or both. Also filters the pattern rules students are offered. |
| Allow problems within 1,000 | Add & Subtract stays inside 100 unless you switch this on, which also adds the ±100 jump buttons. |
| Counting by | Which increments appear in Count. At least one stays switched on. |
| Number labels on the chart | All visible for early in the year, Some hidden (about one in five blank) or Mostly hidden for students who no longer need every label. |
| Ask for a prediction | On: the student must predict before the app moves. Off: moves happen straight away. |
| Let students use the jump buttons | Removes the ±1, ±10, ±100 buttons from Explore if you want tapping only. |
| Show a Random Practice choice | Adds the 🎲 mixed-practice tile to the home screen. |
| Questions in a practice session | 5, 10, 15 or 20. Also sets how many steps a count runs and how many problems Add & Subtract gives. |
| Reset to defaults | Puts everything back to the starting settings. |
The four difficulty levels
| Level | Numbers | Support | Good for |
|---|---|---|---|
| 1 · Build It | to 100 | every number shown | beginning of the year |
| 2 · Practice It | to 200 | some numbers hidden | once 1–100 is secure |
| 3 · Stretch It | to 1,000 | some numbers hidden | working across hundreds |
| 4 · Challenge It | to 1,000 | most numbers hidden | end of year, minimal hints |
Tick Lock the app to this level and the level takes over the number range and the hidden numbers, whatever the settings above say. Untick it and your own choices apply again. This is the quickest way to set one device for a small group.
Teacher Mode — whole group and small group
Tap 📚 Teacher Mode in the top bar. This is a manipulative, not an activity: it never asks a question, never marks anything, and never moves you along. You are in charge of every square.
The toolbar
| Tool | What it does |
|---|---|
| Teaching focus | The menu at the top. Choose the lesson and the toolbar shrinks to just those tools. See the table below. |
| Chart | Full chart, or a 3×3, 4×4 or 5×5 piece of it blown up huge. In a partial chart, choose 🔲 Move window and tap to slide the window around. |
| Tapping a square will… | Sets what your finger does: highlight, shade a whole row or column, hide/show a number, show more & less, set a pattern start, or set a jump start. |
| Highlight colour | Five colours. Tap a square to colour it, tap again to clear it. Use different colours to compare two patterns on one chart. Clear highlights wipes them all. |
| Hidden numbers | Hide all, Reveal all, Hide some (about a third at random), or tap single squares to hide and reveal them one at a time. |
| More & less | Tap a number and 1, 10 and 100 more and less light up in their own colours, with the facts written large under the chart. The buttons move the selection. |
| Pattern tool | Pick a rule (+1, −1, +5, +10, −10, +25, +100, −100), tap a starting number, then Show next to reveal one number at a time. Show all fills the pattern in, Back one steps back, Clear starts over. |
| Manual pattern | Tick it and you tap each number of the pattern yourself — useful when the class is calling out the next number. Tapping the last one again removes it. |
| Jump tool | Tap a starting number, then use ±1, ±10, ±100. Every jump stays on the chart and the equation writes itself: 38 + 10 + 10 + 1 + 1 + 1 + 1 = 62, with the trail and Altogether: 38 + 24 = 62 underneath. Undo jump and Clear jumps are there when you need them. |
| Predict / pause | Tick it and every move stops first on a dark banner: “Where will we land? 59 + 10 = ?” The chart does not move — not even to the next hundred — until you press Reveal. Cancel backs out. |
| Reset | One tap clears highlights, hidden numbers, patterns and jumps, and returns to the 1–100 chart. |
| Hide tools | Collapses the toolbar so the chart has the screen to itself. The ☰ Tools button brings it back. |
| Student home | Hands the device back to the students’ six choices. |
The chart buttons above the chart reach every hundred to 1,000 in Teacher Mode, whatever the student range is set to. Patterns and jumps that cross a hundred move the chart with them, and in a partial chart the window slides along too.
Teaching Focus presets
| Choose | You get |
|---|---|
| All tools | Everything, for open exploring. |
| Counting by 1s / 5s / 10s / 25s / 100s | The pattern tool with that rule already chosen, plus highlighting. |
| 1 More / 1 Less | More & less with only the ±1 buttons. |
| 10 More / 10 Less | More & less with only the ±10 buttons. |
| 100 More / 100 Less | More & less with only the ±100 buttons. |
| Number Patterns | The full pattern tool with every rule. |
| Mystery Numbers | The hiding tools and highlighting. |
| Addition | The jump tool with only the + buttons. |
| Subtraction | The jump tool with only the − buttons. |
Five things to try on the board
1. What happens when we add 10?
Focus: 10 More / 10 Less. Tap 47. Ask what will change before you press +10. Repeat down the column, then ask what stayed the same every single time.
2. Skip counting that leaves a shape
Focus: Counting by 5s. Start at 5 and press Show next repeatedly, asking for the next number each time. Stop halfway and ask what the highlighted squares look like. Then switch the rule to +25 in a second colour and compare.
3. Two ways to solve 38 + 24
Focus: Addition. Jump +1 six times and +10 twice with the class, read the equation, then Clear jumps and do +10, +10, +1, +1, +1, +1 — or bigger chunks. Same answer, different route. Ask which one they would rather use and why.
4. Crossing into the next hundred
Focus: Counting by 10s, predict/pause on. Start at 93. Before each reveal, ask “where will we land?” The chart deliberately stays put until you press Reveal, so the jump from 93 to 103 is a prediction, not a giveaway.
5. Mystery squares
Focus: Mystery Numbers. Press Hide all, then reveal three or four numbers and ask the class to work out a hidden one and explain how they know. Or switch to a 3×3 partial chart and hide the middle square.
On the board, on Chromebooks, on tablets
- Interactive board or projector: use Teacher Mode, press Hide tools for the biggest possible chart, and use a 3×3 or 4×4 partial chart when the back row needs bigger numbers.
- Chromebooks and laptops: the student side is designed for this. Everything is a click; nothing needs a keyboard.
- Tablets: the chart moves to the top and the buttons sit underneath. All controls are finger sized.
- Settings live on the device, not in an account. If you set up a class set of Chromebooks, set each one — or just leave the defaults, which suit most of the year.
- Students never sign in and nothing they do is stored or sent anywhere.
What students are practising
- Counting within 1,000 and skip counting by 5s, 10s, 25s and 100s.
- Mentally finding 10 more, 10 less, 100 more and 100 less than a number.
- Reading three-digit numbers as hundreds, tens and ones, and seeing that 1–100 patterns keep working past 100.
- Identifying, extending, describing and creating patterns made by repeated addition or subtraction.
- Adding and subtracting within 100 (and beyond, if you allow it) by breaking numbers into tens and ones rather than following a memorised procedure.
- Explaining why a move works — the app keeps asking which digit changed and which stayed the same.
Questions you may have
The chart jumped to a different hundred.
That is intended. When a count, pattern or jump crosses 100, 200, 300 and so on, the app moves to the next chart and says so, keeping everything already highlighted. It is how students see that 293 + 10 = 303 is the same move as 93 + 10 = 103.
Some squares are blank.
That is the Number labels setting, or a locked level 2–4. Set it to All visible if a student is not ready for it.
A student is stuck on a question.
Let them try again — the hints get more concrete each time and the third attempt explains the answer and glows the square. Nothing is recorded, so a wrong answer costs them nothing.
Can I stop the app asking for predictions?
Yes — untick Ask for a prediction in Settings. Teacher Mode has its own separate Predict / pause tick box.
My settings disappeared.
Settings are saved per device and per browser. A different computer, a different browser, or clearing browsing data starts from the defaults again.
Can I print this guide?
Yes — the button below prints just this guide, without the app around it.