SPACE ACADEMY · TRY, THINK, PLAY

Class 1: Add, subtract, investigate

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

Play missionChapters

Try a quick challenge

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

ExploreWorking backwards

Asha's scale is level. Which number replaces the question mark?

Asha's scale103?
  1. 7
  2. 10
  3. 6
  4. 3
Need a hint?

Both pans need the same total. Find the known total first.

Answer & method
Answer A: 7

10 = 10; 10 - 3 = 7.

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ReasonSubtraction and change

Which code matches each crossed sample row to its subtraction sentence?

Picture RowsSentencesPQRS(1) 6 - 1 = 5(2) 4 - 2 = 2(3) 5 - 3 = 2(4) 4 - 3 = 1
  1. P1 Q3 R2 S4
  2. P1 Q2 R3 S4
  3. P1 Q2 R4 S3
  4. P2 Q1 R3 S4
Need a hint?

For each row, count the total, the crossed objects and the objects left.

Answer & method
Answer B: P1 Q2 R3 S4

P: 6 - 1 = 5; Q: 4 - 2 = 2; R: 5 - 3 = 2; S: 4 - 3 = 1. The code is P1 Q2 R3 S4.

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StretchSubtraction and change

After both changes, how many more tubes does the fuller crate of Ovi have?

Ovi's cratesTara+0Kabir-3
  1. 4
  2. 2
  3. 6
  4. 3
Need a hint?

Update each crate first, then compare the two final amounts.

Answer & method
Answer B: 2

Tara has 4; Kabir has 2. Their difference is 2.

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For grown-ups

Ideas to practise

  • Working backwards. Undo the last operation first, then undo the earlier operation.
  • Addition and missing amounts. Combine the amounts, or work backwards from the total.
  • Subtraction and change. Start with the original amount and take away what was used.
  • Equal groups and multi-step problems. Find the total in equal groups before applying the next change.

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 Drive unit in Mars Rover Rescue. 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.

  • Repair a part-whole bar
  • Balance two number pans
  • Find the fact-family intruder
  • Cross pictured objects to leave a target amount
  • Match pictured crossings to subtraction sentences
  • Solve a short add or take-away story
  • Pick the number sentence for a story
  • Decide which number sentences are true
Play Explore

Reason

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

  • Balance two number pans
  • Find the fact-family intruder
  • Compare two changed collections
  • Cross pictured objects to leave a target amount
  • Match pictured crossings to subtraction sentences
  • Pick the number sentence for a story
  • Decide which number sentences are true
  • Share equally, or count equal groups
Play Reason

Stretch

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

  • Repair a part-whole bar
  • Balance two number pans
  • Find the fact-family intruder
  • Compare two changed collections
  • Cross pictured objects to leave a target amount
  • Match pictured crossings to subtraction sentences
  • Solve a short add or take-away story
  • Pick the number sentence for a story
  • Decide which number sentences are true
  • Share equally, or count equal groups
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 1 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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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.