Lesson 1163 of 1570
Reasoning Models: When AI Thinks Before It Speaks
OpenAI's o3, Claude with extended thinking, and DeepSeek-R1 actually pause and reason before answering. Slower, smarter, pricier.
Lesson map
What this lesson covers
Learning path
The main moves in order
- 1The big idea
- 2reasoning model
- 3o3
- 4extended thinking
Concept cluster
Terms to connect while reading
Section 1
The big idea
Reasoning models spend extra compute 'thinking' (generating internal reasoning tokens you may or may not see) before producing a final answer. They crush math, hard logic, and code — but cost more and take longer. Use them for problems where being right matters more than being fast.
Some examples
- A tough math contest problem → o3 or Claude extended thinking.
- A Codeforces-level coding challenge → DeepSeek-R1 or o3.
- A research synthesis comparing 20 papers → reasoning model with citations.
- A simple email reply → don't waste a reasoning model on it.
Try it!
Find a hard problem (logic puzzle, contest math). Try Claude or ChatGPT in normal mode and reasoning mode. Compare.
Key terms in this lesson
End-of-lesson quiz
Check what stuck
15 questions · Score saves to your progress.
Tutor
Curious about “Reasoning Models: When AI Thinks Before It Speaks”?
Ask anything about this lesson. I’ll answer using just what you’re reading — short, friendly, grounded.
Progress saved locally in this browser. Sign in to sync across devices.
Related lessons
Keep going
Creators · 10 min
The Reasoning-Model Family: When To Pay Extra For Thinking
The o-series, Opus thinking modes, Gemini Deep Think — reasoning models cost more per token but think before answering. Knowing when to pay is a money-and-time tradeoff.
Creators · 40 min
AI Model Families: Reasoning Models (o-series, Thinking modes) and Their Real Workloads
Reasoning models trade latency for stronger multi-step thinking; route to them only when the task genuinely needs the extra cycles.
Builders · 25 min
Claude Opus 4.7 vs. Sonnet 4.6 — which Claude to pick
Opus is the flagship, Sonnet is the workhorse. Here is the five-minute decision tree for when to pay 2x more for Opus and when Sonnet handles it.