Input, processing and output — App development for students

Developer's tip

In, work, out — “the user gives input, the app processes it, the user gets output”

1. Input → processing → output.
2. Input: typing, tapping, a photo, your voice. Output: a result on screen, a sound, a buzz, a pop-up.
3. In code, the processing line works out a new value from the inputs; show() is the output.

Use it for: Planning what each screen of your app takes in and gives back.

Worked example: ⚙️ Which line does the processing (works out the answer)?
line 1: let price = 35; // typed by the user
line 2: let qty = 3; // typed by the user
line 3: let total = price * qty;
line 4: show(total); → line 3

✏️ Practice

Work it out in your head or on paper, type the answer and press Check. Stuck? Press “Show me how”.

🏁 Lesson 7 test

20 questions. Check each answer, then go to the next one. Get 16 or more right to pass.

🏅 Sign in with Google to earn the ⚙️ Input-Output Wizard badge when you pass — and a certificate when you finish all 8 lessons of Part 1 · What Apps Are. You can still take the test without signing in.

🖨️ App Dev Worksheet: Input, Processing, Output

• Worksheet set 1 (PDF)
• Worksheet set 2 (PDF)
• Worksheet set 3 (PDF)