Rocket builds a lamp with two switches. "It should glow only when both switches are on!" he says.
He flips the switches fast. Click, click, click. The lamp blinks on and off.
"Let's slow down," Raven says. "How many ways can two switches be set?" Nova glows softly. "Try writing each way on its own row," she says. Let's fill in the tables.
A TRUTH TABLE shows every combination. Fill in the answers (T or F).
| A | B | A AND B |
|---|---|---|
| T | T | ? |
| T | F | ? |
| F | T | ? |
| F | F | ? |
| A | B | A OR B |
|---|---|---|
| T | T | ? |
| T | F | ? |
| F | T | ? |
| F | F | ? |
| A | NOT A |
|---|---|
| T | ? |
| F | ? |
Use the rules. AND is TRUE only when both parts are TRUE. OR is TRUE when at least one part is TRUE.
| A | B | A AND B |
|---|---|---|
| T | T | ? |
| T | F | ? |
| F | T | ? |
| F | F | ? |
| A | B | A OR B |
|---|---|---|
| T | T | ? |
| T | F | ? |
| F | T | ? |
| F | F | ? |
Now mix them. In A AND NOT B, first flip B. Then use AND.
| A | B | A AND NOT B |
|---|---|---|
| T | T | ? |
| T | F | ? |
| F | T | ? |
| F | F | ? |