Anatomy of a Standard Part: teacher key

How Plastic Toy Bricks Are Made, grade 12 edition, written for 12th grade and up. A study of the interlocking plastic brick as an engineered object: a disputed patent history, rubber-toughened plastic, steel molds and measurements that sources report differently. It ends with the plastic itself, from the factory floor to the trash bin. Figures are dated where they can change.

Read the book. Print this page for the key.

Questions and answers

1. Which ABS ingredient adds toughness?
   • Acrylonitrile
   • Styrene
   • Polybutadiene (answer)
2. Why do aluminum molds suit low volumes?
   • They wear, dent and deform more easily than steel (answer)
   • They are harder than steel
   • They cost more to make
3. What did the Open University brick do under load?
   • Shattered at once
   • Failed by plastic deformation without shattering (answer)
   • Melted
4. Why does the book say the figures for precision should be read as rough and dated?
   • Sources report different tolerances from different years (answer)
   • No bricks were measured
   • The figures come from one report
5. In this book, what does crazing refer to?
   • A cooling line
   • A mold's worth
   • A process that starts at rubber particles and strengthens the plastic (answer)

Words

• polybutadiene: rubbery ingredient
• amorphous: no melting point
• crazing: starts at particles
• tolerance: allowed error
• cavity: hollow space