The Sandwich Method: teacher key

How Pencils Are Made, grade 7 edition, written for 7th grade. Inside the pencil factory: slats, grooves, glue, presses and the eraser at the end.

Read the book. Print this page for the key.

Questions and answers

1. What did K. W. Scheele show in 1779?
   • The core is pure carbon (answer)
   • The core is lead
   • The core is clay
2. What holds the sheets of graphite to each other?
   • Strong bonds
   • Glue
   • Weak bonds (answer)
3. What happens in the hydraulic press?
   • The sandwich is clamped until the glue dries (answer)
   • The cores are baked
   • The wood is painted
4. Why do diamond and graphite behave so differently?
   • Their atoms are arranged differently (answer)
   • They are different elements
   • One is wetter
5. What is a ferrule?
   • A round metal case (answer)
   • A kind of glue
   • A grade of pencil

Words

• graphite: soft carbon form
• ferrule: metal band
• slat: thin board
• hexagonal: six-sided