Teach me the 80/20 of {{topic}}.

My current level: {{current_level}}
Time I have to dedicate: {{time_available}}
Why I want to learn it: {{why}}

Identify the 20% of concepts that deliver 80% of the value for my goal.

For each concept:
1. Explain it in 2-3 sentences
2. Show one concrete example
3. Give me one exercise I can do today

Skip theory I don't need. Be ruthless about cutting. End with the single biggest mistake beginners make.