Churn lid with hole and smartphone: what they have in common

1. Step 1. Churn lid with hole — is part of — Butter churn. It lets the dasher’s shaft through.
2. Step 2. Butter churn — uses — Lever. A dasher.
3. Step 3. Lever — is used in — Joystick. A lever.
4. Step 4. Joystick — evolved into — Gamepad. A game controller.
5. Step 5. Gamepad — has part — Vibration motor. Vibration.
6. Step 6. Vibration motor — is part of — Smartphone. A tiny motor produces the vibration alert.

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