Truth Tables — Mapping Every Case (Grades 7–8)
A truth table lists every combination of true/false inputs and the resulting output, so nothing is missed. For two inputs there are 4 rows. For "A AND B," the output is true only in the single row where both are true; for "A OR B," it's true in three rows (false only when both are false).
Understanding truth tables
A truth table lists every combination of true/false inputs and the resulting output, so nothing is missed. For two inputs there are 4 rows. For "A AND B," the output is true only in the single row where both are true; for "A OR B," it's true in three rows (false only when both are false).
Key Idea
A truth table lists every combination of true/false inputs and the resulting output, so nothing is missed. For two inputs there are 4 rows. For "A AND B," the output is true only in the single row where both are true; for "A OR B," it's true in three rows (false only when both are false).
Seeing it in action
Worked example
For "A AND B," in how many of the 4 rows is the output true?
True only when A=true and B=true → 1 row.
List every true/false case so none are missed.
Try a few
"A OR B": how many of 4 rows are true?
"A AND B" when A=true, B=false?
"A OR B" when A=false, B=false?
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