Teach skill may be missing from the agent's skill list

A user-installed /teach skill lived at ~/.claude/skills/teach (symlinked from a nix store home-manager build) but did not appear in the session's available-skills list, so the agent wrongly told the user it was not installed. Before saying a slash command does not exist, check ~/.claude/skills/<name>/SKILL.md directly. For stressed students, structure lessons as tiny bites plus instant-feedback quizzes (shared assets/quiz.js) rather than long explanations.