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简体中文For teachers
Estimation activities for the classroom
Free printable activity sheets that use real sizes, from a single cell to a mountain, to practise estimating, measuring and comparing. Every sheet has teacher notes with the answers.
Print and copy them for your classes as often as you like. Each comes in A4 and US Letter.
Printable activity sheets
Students estimate first and then check with real numbers. The teacher pages work out every answer from the same sizes that are on the sheet.
Line them up: prehistoric animals by length
Comparing and ordering lengths · metres · how many times longer
Six prehistoric animals, all drawn the same size so the picture cannot give the answer away. Students guess their order from shortest to longest, check against the real lengths, work out how many times longer one animal is than another, and mark out two of them in the playground.
The teacher page has the answers and all six animals drawn to true scale on one ruler.
How many fit? Food and fruit
Millimetres and centimetres · division · ratio
Six questions that pair a small food with a bigger one, drawn to scale: how many grapes reach across a pizza, how many grains of rice, how many peas make the height of an egg. Students estimate by eye, then divide. A second page has them measure real food with a ruler, and a challenge asks how many blueberries would fill a watermelon.
The teacher page has worked answers, including why a watermelon twenty blueberries wide holds thousands of them.
Powers of ten: from a cell to a mountain
Standard form · orders of magnitude · logarithmic scales
Nine things, from a white blood cell to Mount Fuji. Students write each size in metres in standard form, place them on a logarithmic scale from 1 µm to 10 km, and work out how many times bigger one is than another. The biggest is more than 500 million times the smallest.
The teacher page has every size in standard form, the ratios and the number of powers of ten between the smallest and the biggest.
Fermi problems: estimate like a scientist
Fermi estimation · unit conversion · volume · orders of magnitude
Five problems built on real sizes: grains of rice to the top of a coast redwood, blueberries in a watermelon, stairs up Mount Fuji, liver cells along a ruler and a tower of students as tall as Uluru. Students break each question into steps, state their assumptions and judge the answer by its order of magnitude.
The teacher page has worked estimates and notes on which answers count as good ones.
How to use the game in class
Ask for an estimate before any measuring or calculating, and talk about the misses. A guess ten times too big is a different kind of mistake from a guess twice too big.
The Magnitudle app asks the same kinds of questions: order things by size, pick the biggest, resize things to real scale and say how many of one thing fit into another. Levels have no time limit, so students can think each answer through; the daily challenge and multiplayer rounds are timed. Size guesses are scored by ratio, so a guess twice too big and a guess half the true size lose the same points. See how scoring works.
For a group, one player can host a private room that the others join with a code: up to eight players, and the host can add bots at four levels of difficulty. There is no chat; players can only send a fixed set of short reactions such as “GG” and “Nice one”. More on the multiplayer modes.
Students can play as guests with just a nickname, and switch sizes between metric and imperial units in the settings. The app is available in English, Ukrainian, German, Polish, Spanish, Italian, Turkish, Brazilian Portuguese, French, Japanese, Korean, Simplified Chinese, Russian, Arabic, Hindi, and Indonesian.
The app is free on iPhone and Android: get Magnitudle.
Age suitability
The sheets are written for ages 7 to 16, and each one shows its own age range. Younger students can do the ordering and measuring tasks with help; older students can go straight to standard form and Fermi problems.
The game's age rating is on its App Store listing and its Google Play listing. Before students use the app, read our privacy policy: playing creates an account with a nickname, and the account can be deleted from the app's profile screen.
Estimation and measurement topics covered
- Comparing and ordering lengths
- Measuring in millimetres, centimetres and metres, and converting between them
- Metric and imperial units side by side
- Division and ratio: how many fit, how many times bigger
- Standard form and powers of ten
- Reading a logarithmic scale
- Scaling from length to volume: twice as wide holds eight times as much
- Fermi estimation: breaking a big question into small steps
For the techniques behind good estimates, see how to estimate sizes better.
Where the numbers come from
Every size on the sheets comes from the Magnitudle catalogue of sizes, rounded. Extinct animals are known from fossils, so their sizes are estimates. The silhouettes were generated with AI and traced to outlines: they show shapes, and no number is taken from them.
How we measure sizes explains how items are made and checked. Found a mistake? Tell us.
Free on iPhone and Android
Try the questions yourself first
The quickest way to prepare is to play a few rounds before the lesson.
