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Education Concept Tracker

A prerequisite knowledge graph of 1590 learning concepts across 8subjects. Track what you've mastered and see exactly what you're ready to learn next — the topics whose prerequisites you've already met. Built on the Marble Open Skill Taxonomy.

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Mental addition and subtraction (age 6+)

Mathematics · Addition & Subtraction · procedural

Add and subtract a two-digit number and ones mentally and using concrete/pictorial representations

What mastery looks like

  • Calculate 36 + 7 = 43 using objects or mentally
  • Calculate 52 − 4 = 48 using a number line or mentally
  • Explain bridging through 10 when adding ones to a two-digit number

Check your understanding

Can Mental addition and subtraction (age 6+) work out '36 + 7' or '42 − 5' in their head — keeping the tens in place and only adjusting the ones?