Compass legs and truck: what they have in common

1. Step 1. Compass legs — is part of — Compasses. A needle and a lead holder.
2. Step 2. Compasses — uses — Lever. Two legs on a hinge.
3. Step 3. Lever — is used in — Stretcher. Two poles — levers for carrying.
4. Step 4. Stretcher — is part of — Ambulance. A stretcher.
5. Step 5. Ambulance — evolved from — Truck. A special-purpose vehicle.

Open Evothings