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Coding · Grade 3

Algorithms and Decomposition

Third graders decompose big tasks into sub-tasks, split long robot routes into legs programmed as loops, learn linear search (and how sorted lists let a search stop early), and compare algorithms by counting their worst-case steps.

  • 4 lessons
  • About 80 minutes
  • Algorithms check: 8 questions
  • Ways to answer: program with blocks, choose an answer, type a number, put in order and sort into groups
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What learners will discover

  • Decompose a big task into smaller sub-tasks and order them.
  • Decompose a long robot route into legs and program each leg.
  • Carry out a linear search and explain how a sorted list lets the search stop early.
  • Compare two algorithms for the same task by counting their steps in the worst case.

Lessons

  1. Break a big task into parts 4 steps2 practiceabout 16 min
  2. Decompose a route into legs 4 steps2 practiceabout 16 min
  3. Search algorithms 6 steps3 practiceabout 16 min
  4. Compare algorithms 6 steps3 practiceabout 16 min
  5. Algorithms check 8 questions at the end

Keep exploring

Games to practice with

  • Robot RoutesSnap together arrow, repeat and dance blocks to guide Bolt the robot home.
  • Bug DetectiveA robot program almost works. Run it, spot the buggy block, and fix it.
  • Sorting FactoryTurn a work order into if/else rules and watch the conveyor sort every item.

More 3rd grade coding

Guide for grown-ups