SPACE ACADEMY · TRY, THINK, PLAY

Class 3: Measure the mission

Read scales and rulers, compare like units and infer unknown measurements.

Try a quick challenge

Just a quick try. Not saved; no game rewards.

ExploreMeasurement and conversions

A trail goes through C, D, F, K in order. How far is it from F to K in kilometres?

20 km15 km?CDFKC to K: 55 km
  1. 15
  2. 55
  3. 20
  4. 35
Need a hint?

The parts add up to the whole trail. Take the parts you know away from the whole.

Answer & method
Answer C: 20

55 − 35 = 20 km.

Try more in game

ReasonMeasurement and conversions

How many grams heavier is box Y than box X?

02004006008001000Box X (g)02004006008001000Box Y (g)
  1. 601
  2. 600
  3. 1000
  4. 800
Need a hint?

Read each dial pointer at its mark. Then work out the answer.

Answer & method
Answer B: 600

800 − 200 = 600 g.

Try more in game

StretchMeasurement and conversions

Which mass fits a watermelon?

  1. 3 kg
  2. 3 mg
  3. 30 kg
  4. 3 g
Need a hint?

Pick the unit that matches the real size of the object.

Answer & method
Answer A: 3 kg

3 kg is a sensible measure here.

Try more in game
For grown-ups

Ideas to practise

  • Measurement and conversions. Use the same unit before adding or comparing measurements.
  • Routes and constraints. Follow only the allowed paths. At a junction, add the ways arriving from its incoming paths.

A game mission has 8 untimed questions. Only the game saves choices and hints. A finished mission earns one launch charge and participation towards the Star compass in Star Navigator. The chapter goal is 8 different questions in finished sets; hints and wrong answers count as participation, not mastery. Some craft systems link more than one chapter.

Choose a level

Explore

Foundations: read a representation and practise the underlying idea.

  • Read a length between two ruler marks
  • Read a thermometer or dial scale
  • Find the missing mass on a balance
  • Choose a sensible unit or convert it
  • Add or take away litres, kilograms and metres
  • Find the longest or heaviest of four amounts
  • Pick the closest real-life amount
  • Read two dial scales and work out a mass
  • Find a missing part of a trail
Play Explore

Reason

Paper-style reasoning: connect clues, interpret a diagram or work backwards.

  • Read a thermometer or dial scale
  • Find the missing mass on a balance
  • Fill a jug using equal cups
  • Add or take away litres, kilograms and metres
  • Pick the closest real-life amount
  • Read two dial scales and work out a mass
  • Find a route length on a road map
  • Find a missing part of a trail
  • Find the longest or heaviest of four amounts
Play Reason

Stretch

Higher-order practice: link conditions, test statements and avoid a tempting wrong method.

  • Add or take away litres, kilograms and metres
  • Read two dial scales and work out a mass
  • Find a route length on a road map
  • Find a missing part of a trail
  • Find the longest or heaviest of four amounts
  • Pick the closest real-life amount
  • Find the missing mass on a balance
  • Fill a jug using equal cups
  • Choose a sensible unit or convert it
  • Read a length between two ruler marks
Play Stretch

Levels change representations, clues and conditions, not just the numbers. These are practice formats, not validated exam-equivalent difficulty.

Using the feedback

Learning reports distinguish hinted answers from independent first choices. They consider up to 20 recent different, unhinted questions per skill and level, and wait for at least five before suggesting extra practice. Repeating the same question does not add evidence. Reports are practice evidence, not IQ scores, diagnoses, ranks or predictions of competition results.

Ask the learner to explain a drawing or check with objects too. Choose Explore or an earlier chapter when a step feels too large.

Sources & limits

The grade topics use SOF IMO Class 3 published topic syllabus as their primary reference. The SOF sample and CREST previous-year paper below informed representations and reasoning demands. Providers have different topic boundaries; their syllabi are not interchangeable.

Questions, diagrams, picture choices, hints and explanations are original Otterly work, not copied paper questions or publisher artwork. No Olympiad provider is affiliated with or endorses Space Academy. This is not complete exam preparation; follow classroom teaching and check the current official syllabus too. Independent educator review is still needed for difficulty and breadth.

Content and coverage notes. To report a confusing question, describe the grade, chapter, level and question on the contact page. Do not send children’s personal information.

Private, local saves

Game progress stays only in this browser, in three anonymous explorer slots. Clearing site data or closing a private session may remove it. Download a private backup from Help & saves; there is no cloud sync. The game checks saves before play and stops on save failures rather than pretending progress was saved.

These page examples never change a saved game. Game links carry question settings, not a learner’s answers. There are no names, school details, public profiles, chat, analytics or advertising SDKs in the game. Grown-up guidance · Privacy

Original Otterly practice, not an official exam. Game progress stays on this browser.