Simple explanation
Welcome to Day 3. Today you learn about the most underused feature in Claude Code — Plan Mode. Most beginners skip this. The ones who use it make far fewer mistakes. What is Plan Mode? Normally when you type a prompt — Claude Code immediately starts making changes to your files. It acts first. It thinks as it goes. Plan Mode changes this completely. In Plan Mode Claude Code can only think. It cannot touch a single file. It cannot run a single command. It just reads everything and writes out exactly what it plans to do — and then waits for your approval. You review the plan. You say yes or no. Only then does it act. Why this matters for non-developers When you ask Claude Code to make a complex change — it might touch 5 different files to do it. Without Plan Mode you do not know which files it changed until something breaks. With Plan Mode you see the full picture first: which files it plans to change, what it plans to do in each one, and what the end result should look like. You can catch problems before they happen. Not after.
What to do
How to turn on Plan Mode Inside a Claude Code session — press Shift + Tab twice. You will see the mode indicator at the bottom of the screen change to show Plan Mode is active. Windows users: if Shift + Tab does not work, try Alt + M instead. How to use it 1. Turn on Plan Mode before any prompt that will change more than one thing. 2. Type your prompt exactly as you normally would using the 4-part formula from Day 2. 3. Claude Code will respond with a detailed plan — but it will not do anything yet. 4. Read the plan. Check it makes sense. If something looks wrong — tell Claude Code to adjust the plan before it starts. 5. When you are happy — press Shift + Tab again to return to normal mode and type "go ahead." When to use Plan Mode vs normal mode Normal mode — simple one-file changes. Changing a color. Updating text. Small edits. Plan Mode — anything that touches more than one thing. Adding a new page. Building a new feature. Fixing a complex error. When in doubt — use Plan Mode. Today's practical task: Open Claude Code in your my-first-site folder. Turn on Plan Mode with Shift + Tab twice. Ask Claude Code to add a navigation bar to your homepage with links to Home, About, and Contact. Read the plan it produces. Approve it and watch it build.
Copy-paste prompt
I want you to plan this before doing anything. Do not make any changes yet — just write out exactly what you plan to do. Add a contact form to the homepage with fields for name, email, and message, and a submit button. Tell me: which files you will change, what you will add to each one, and what the result will look like.
Course note
Key takeaway
Plan Mode stops Claude Code from acting until you approve the plan. Use it before any change that touches more than one thing — it prevents most of the expensive mistakes beginners make.