Fetch, Execute, Repeat: teacher key

How Computers Work, grade 4 edition, written for 4th grade. Follow a computer as it runs a program, keeps its memory and stores a picture in bits.

Read the book. Print this page for the key.

Questions and answers

1. What does the CPU do in its cycle?
   • Fetches, then executes (answer)
   • Saves, then prints
   • Sleeps, then wakes
2. What happens to RAM when the power is turned off?
   • It makes bits
   • It loses what it holds (answer)
   • It keeps all files
3. How many bits are in a byte?
   • 8 (answer)
   • 16
   • 4
4. Why can a computer store a picture with only 0s and 1s?
   • A picture is a long list of numbers (answer)
   • A picture is a magnet
   • A picture is a program
5. What is a picture on a computer screen made of?
   • Tiny squares called pixels (answer)
   • Spinning disks
   • Magnets

Words

• fetches: goes and gets
• executes: carries out
• pixels: tiny squares
• binary: zeros and ones