SPACE ACADEMY · TRY, THINK, PLAY

Class 3: Mission mathematics

Interpret models, find unknown amounts and link operations instead of only calculating a total.

Try a quick challenge

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

ExploreEqual sharing

45 pupils are put equally into 5 vans. How many pupils are in each of the vans?

  1. 10
  2. 5
  3. 40
  4. 9
Need a hint?

Share equally by dividing the total.

Answer & method
Answer D: 9

45 ÷ 5 = 9.

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ReasonWorking backwards

What is (9 + 7) × 9 − 5?

  1. 139
  2. 144
  3. 67
  4. 140
Need a hint?

Do the brackets first. Then multiply. Then take away.

Answer & method
Answer A: 139

9 + 7 = 16. 16 × 9 = 144. Then − 5 = 139.

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StretchWorking backwards

Leo and Leo's father are 36 years old together. The father is 10 years older than Leo. How old is Leo?

  1. 26
  2. 13
  3. 18
  4. 23
Need a hint?

Take the age gap away, then share equally.

Answer & method
Answer B: 13

36 − 10 = 26. Share equally: 13.

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For grown-ups

Ideas to practise

  • Equal groups and multi-step problems. Find the total in equal groups before applying the next change.
  • Addition and missing amounts. Combine the amounts, or work backwards from the total.
  • Equal sharing. Divide into equal groups. Check by multiplying your answer by the number of groups.
  • Working backwards. Undo the last operation first, then undo the earlier operation.
  • Subtraction and change. Start with the original amount and take away what was used.
  • Comparing quantities. Compare the values, not the size or spacing of their pictures.

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 Cruise engine 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.

  • Count crates in equal tray rows
  • Find the missing part of a bar model
  • Share supplies and count what is left
  • Multiply rows and groups in a story
  • Divide, and decide what the remainder means
  • Add or subtract big numbers in a story
  • Fill a missing digit in a column sum
Play Explore

Reason

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

  • Find the missing part of a bar model
  • Share supplies and count what is left
  • Fill a missing digit in a column sum
  • Find linked shape values from two lines
  • Multiply rows and groups in a story
  • Divide, and decide what the remainder means
  • Add or subtract big numbers in a story
  • Work backwards to the amount at first
  • Work out a sum with brackets and several signs
  • Find what shapes stand for from picture sums
  • Find a hidden digit in a division
Play Reason

Stretch

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

  • Find linked shape values from two lines
  • Work backwards to the amount at first
  • Solve an age story
  • Work out a sum with brackets and several signs
  • Find the largest value among sums and shares
  • Divide, and decide what the remainder means
  • Fill a missing digit in a column sum
  • Multiply rows and groups in a story
  • Add or subtract big numbers in a story
  • Find what shapes stand for from picture sums
  • Find a hidden digit in a division
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.

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