Module 1: Algorithm Intuition & Visualization: Mistake Clinic

This clinic turns wrong moves into reusable judgment. Use it after each practice page and again before the quiz or checkpoint.

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Module-Specific Mistake Radar

Start with these traps. Replace or extend them with real mistakes from your own work.

Mistake to look for	Where it shows up	Symptom	Repair evidence
Finishing Trace Search and Data Tradeoffs with only a final answer	Trace Search and Data Tradeoffs	The work has no failed case, trace, test, proof gap, or design stress point.	Add the smallest broken example and show the repair that changes the result.
Finishing Trace Recursion and Sorting by Hand with only a final answer	Trace Recursion and Sorting by Hand	The work has no failed case, trace, test, proof gap, or design stress point.	Add the smallest broken example and show the repair that changes the result.
Finishing Build a Graph and Explain the Path with only a final answer	Build a Graph and Explain the Path	The work has no failed case, trace, test, proof gap, or design stress point.	Add the smallest broken example and show the repair that changes the result.
Treating Search by Eliminating Half the Possibilities as vocabulary instead of a tool	Search by Eliminating Half the Possibilities	The explanation names the concept but cannot decide between two cases.	Write one example, one non-example, and the rule that separates them.
Treating Growth Rate Beats Raw Timing as vocabulary instead of a tool	Growth Rate Beats Raw Timing	The explanation names the concept but cannot decide between two cases.	Write one example, one non-example, and the rule that separates them.
Treating Data Shape Controls What Feels Fast as vocabulary instead of a tool	Data Shape Controls What Feels Fast	The explanation names the concept but cannot decide between two cases.	Write one example, one non-example, and the rule that separates them.

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Practice Mistake Checks

Pull any miss from these checks into your mistake log.

Trace Search and Data Tradeoffs

Source: practice/01-trace-search-and-data-tradeoffs.md

If you wrote "hash tables are always O(1)" without saying "average case" or without mentioning collisions, your explanation is too loose. If you wrote "binary search is faster" without naming sorted order, your explanation is incomplete.

Trace Recursion and Sorting by Hand

Source: practice/02-walk-a-recursive-algorithm.md

If your recursive step does not move toward a smaller problem, it is probably broken. If your selection sort trace never shows a full scan for the next smallest item, it is incomplete. If your quicksort explanation never mentions partitioning around a pivot, you are skipping the key idea.

Build a Graph and Explain the Path

Source: practice/03-build-a-graph-and-explain-the-path.md

If your search revisits the same node endlessly, you forgot the visited rule. If your explanation claims BFS solves all shortest-path problems, it is too broad. State that it handles shortest path in number of steps for unweighted edges.

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Repair Protocol

For each real mistake:

1. Reproduce the failure on the smallest example, trace, proof, query, command, or design sketch.
2. Name the hidden assumption.
3. Repair the artifact.
4. Save evidence that changed: failing then passing test, corrected proof step, revised diagram, safer command, benchmark, or review note.
5. Add one retrieval card beginning with Check... before... or Do not use... when....

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Mistake Log

Date	Mistake	Symptom	Root cause	Repair evidence	Retrieval card
Starter	Pick one radar row above	Explain how it would fail in this module	Name the assumption	Add a counterexample or corrected artifact	Write the card before closing the page

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Completion Standard

• At least five real mistakes are logged.
• At least two mistakes include a counterexample or failing test.
• At least one mistake connects to an older semester skill.
• At least one correction changes code, a proof, a diagram, a command transcript, a query, or a design decision.