To bring awareness to the number of different materials that are combined to create an object.
An LCD wristwatch
The most important thing in this exercise is not to correctly name all the materials, but to realize how many man-made materials makes up even a simple watch.
1. Hold up a wristwatch. Ask How many materials have been used to make it?
2. List the parts of the watch (band, case, screws, etc.)
3. Tell them all these parts fall into three groups of materials - metals, plastics, or ceramics. Ask them to categorize the parts under the three headings. (This list may vary with the particular watch being used.) Metals: case, band, clasp, screws, gold pated contacts. Plastics: wrist band, clear plastic window, rubber seal wings. Ceramics: crystal oscillator (little clock), piezo crystal speaker (makes beeping noise).
4. Repeat this with other objects.
What would happen if the entire watch was made only of metal? Would it work? Would you be able to read the time? Why are different materials important?