Lesson 13 of 1570
Chain-of-Thought: Make the AI Show Its Work
Telling the AI to 'think step by step' before answering dramatically improves its accuracy on reasoning problems. Here's why and when.
Lesson map
What this lesson covers
Learning path
The main moves in order
- 1The four magic words
- 2chain-of-thought
- 3step-by-step reasoning
- 4show your work
Concept cluster
Terms to connect while reading
Section 1
The four magic words
Adding 'think step by step' or 'let's work through this carefully' to a prompt can flip an AI from wrong to right on math, logic, and planning problems. Researchers call this technique chain-of-thought, or CoT.
With and without CoT
CoT turns a guess into a verifiable chain.
WITHOUT CoT:
Q: A shirt costs $20 and is 25% off. Then you use a $5 coupon on the discounted price. What do you pay?
A: $10. <-- often wrong
WITH CoT:
Q: A shirt costs $20 and is 25% off. Then you use a $5 coupon on the discounted price. What do you pay? Think step by step.
A:
- Original price: $20.
- 25% of $20 is $5.
- Discounted price: $20 - $5 = $15.
- Apply $5 coupon: $15 - $5 = $10.
Final answer: $10. <-- shows reasoning, more reliably correctHere the final number is the same, but with CoT you can check each step. If a step is wrong, you see it. Without CoT, the AI could give you '$15' and you wouldn't know why.
Phrasings that trigger CoT
- 'Think step by step.'
- 'Let's reason through this carefully.'
- 'Before giving your final answer, write out your reasoning.'
- 'Work it out one piece at a time.'
- 'Show your thinking as a numbered list, then give the answer.'
When to use CoT
Compare the options
| Use CoT | Skip CoT |
|---|---|
| Multi-step math. | Quick factual lookup. |
| Logic puzzles. | Creative writing. |
| Planning and scheduling. | Short answers or summaries. |
| Comparing options. | Simple translations. |
| Anywhere getting it wrong would matter. | Anywhere speed matters more than accuracy. |
Structured CoT — you can verify each step.
You are a careful tutor. A student asks:
"I have 3 tests coming up. Math is worth 20%, Science is worth 35%, and History is worth 45% of my grade. If I scored 92, 78, and 85 respectively, what's my final grade?"
Before you give a final number:
1. Write out what each score contributes.
2. Show the math.
3. Only then give the total.
Format:
**Step 1:** ...
**Step 2:** ...
**Step 3:** ...
**Final grade:** ...Key terms in this lesson
End-of-lesson quiz
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