1. Nowadays, asbestos is rarely intentionally added to teaching instruments. However, asbestos pollution or residues in old instruments cannot be completely ruled out.

2. Some industrial teaching instruments, especially early equipment, may use asbestos as thermal insulation material. There is a risk of asbestos in this case.

3. The old teaching mode may also contain asbestos, which needs careful examination and identification.

4. If there is an old coating on the surface of the teaching instrument, the coating composition should be tested, which may contain asbestos.

5. The internal structure of teaching instruments is complex, and asbestos pollution is hidden. Professional institutions are needed for disassembly and testing.

6. The shells and buttons of teaching instruments may also be contaminated by asbestos particles, which requires wet cleaning and dust removal.

7. If the surface of the instrument falls off, it must be stopped for testing to avoid the spread of asbestos fibers.

8. For teaching instruments with a long service life, it is recommended to carry out harmless treatment or gradually scrap them, and do not continue to pile them up for use.

9. Asbestos-free products should be selected when purchasing new instruments, and asbestos test reports are required.

To sum up, it is necessary to be alert to the potential asbestos risks of teaching instruments and take measures such as testing and replacement.