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Museion Original · Computer Science

extension · Ages 14+ · intro programming

Recursion: Trust the Smaller Case

A base case, and every call moving toward it.

Start the path 4 lessons · about 55 minutes
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Four connected investigations

  1. 01Base Case and ProgressFor learners ages 14+ starting recursion: a correct recursive definition needs a base case, and every recursive call must move the input toward it.Open
  2. 02Tracing the Call StackFor learners ages 14+ who understand base case and progress: hand-trace a recursive function's return value, see when work happens on the way down versus the way back up, and count stack depth precisely.Open
  3. 03Near Transfer: A New Recursive DefinitionFor learners ages 14+ who can trace base case, progress, and unwind order: apply that same reasoning to a brand-new recursive definition, power(b, e), and to a fresh doubling context.Open
  4. 04The Recursion Lab: Build It, Watch It RunComplete two recursive functions slot by slot, watch the call stack respond, and see exactly why a bad recursive argument never stops.Open

What this path asks you to reason about

  • State why a recursion needs a base case and progress toward it.
  • Hand-trace a recursive call stack and its returned value.
  • Predict a fresh recursive definition's value and spot non-termination.