teachingpiece

2. A short written work or passage used for instruction.

The story was a teaching piece about kindness.

3. A sample or model shown to explain how something works.

The engineer brought a teaching piece to demonstrate the engine.

4. A piece of music chosen to help a student practice a skill.

This etude is a teaching piece for beginners.

5. An object in a museum used to explain history to visitors.

The old coin served as a teaching piece in the history exhibit.