Numbers Behind the Screen: teacher key

How Computers Work, grade 5 edition, written for 5th grade. How a computer keeps a picture in bits, where the bits are stored, and how pictures and sound get squeezed.

Read the book. Print this page for the key.

Questions and answers

1. Where does a computer copy a program before it runs?
   • Into RAM (answer)
   • Onto a mouse
   • Into a pixel
2. What does each extra bit do to the number of patterns?
   • Doubles it (answer)
   • Halves it
   • Erases it
3. What is compression?
   • Adding two numbers
   • Turning off RAM
   • Squeezing pictures and sound into less space (answer)
4. How is a bit stored on a hard disk?
   • As magnetism (answer)
   • As electric charge
   • As a pixel
5. Why are saved files still there after the power goes off, but RAM is not?
   • RAM is a chip
   • A drive keeps saved files, and RAM loses what it holds (answer)
   • A drive is faster

Words

• compression: squeezing data
• binary: two-digit system
• pixels: tiny squares
• RAM: fast memory