Blackboard and rock drill: what they have in common

1. Step 1. Blackboard — uses — Chalk. People write with chalk.
2. Step 2. Chalk — is material for — Tablet (medicine). Tablet fillers are chalk and starch.
3. Step 3. Tablet (medicine) — works like — Capsule. Dosage forms.
4. Step 4. Capsule — is part of — Pneumatic tube. A container for letters.
5. Step 5. Pneumatic tube — uses — Compressed air. Air pressure.
6. Step 6. Compressed air — is used in — Rock drill. Pneumatics.

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