What we are making: one page, for one named person, doing one job. No new hardware — this is a design session and a rehearsal for the project.

Pick a person, not a feature

Choose somebody real and write their name down. The caretaker. A parent at the exhibition. Your grandmother. Then answer three questions about them:

1. What do they need to know in four seconds? One thing. Not three.
2. What, if anything, should they be able to do? Often nothing, and that is a fine answer — a page with no buttons is easier to use than one with five.
3. What would make them distrust it? A number with no units. A reading with no age. A button that does nothing visible.

Build it

4. Use any of the sensors and outputs from Unit B. Nothing new.
5. Build the page for your person, following your three answers.
6. Put the age of the reading on it, always.
7. Test it on somebody who is not on your team, in silence, and fix what you see.

The hand-in

• Your device, working, on the school WiFi or its own hotspot.
• The name of the person you designed it for.
• Your three answers, written before you built it.
• One sentence on what the device cannot do.
• One thing the stranger got wrong, and the change you made.

What you learned

• Designing for a named person is easier than designing for everybody.
• Fewer controls is usually better than more.
• You can now build a networked device somebody else can use. That is the year.