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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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Knowledge-graph map

Computing
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Measuring length

Mathematics · Measurement · procedural

Order three objects by length and compare the lengths of two objects indirectly using a third object

What mastery looks like

  • Put three ribbons in order from shortest to longest
  • Use a piece of string to compare the heights of two objects that cannot be placed side by side
  • Explain that if A is longer than B and B is longer than C, then A is longer than C

Check your understanding

If Measuring length has three pencils of different lengths but can only compare two at a time, can they figure out which is longest — by using a third pencil as a go-between?