Boolean Logic Masterclass

J277 Specification Reference: 2.4 Boolean logic

Learning Objectives

Recognise and draw standard logic gate symbols (AND, OR, NOT). Complete truth tables for 2-input and 3-input logic systems. Create, complete and edit logic diagrams from scenarios. Apply logical operators to solve problems.

Why this matters

Computers make decisions using simple True/False rules, just like strict parents.

Rule 1: AND (Strict)

"You can play if you have finished homework AND tidied your room."

Homework + Room = Play

Rule 2: OR (Relaxed)

"You can play if it is the weekend OR if it is a holiday."

Weekend = Play

1. Core Knowledge: The Gates

TAP CARDS TO FLIP

AND

Tap for definition

AND Gate

Output is 1 only if BOTH inputs are 1.

AKA: Conjunction

OR

Tap for definition

OR Gate

Output is 1 if EITHER inputs are 1.

AKA: Disjunction

NOT

Tap for definition

NOT Gate

Output is the INVERSE of input.

Don't forget the circle!

Checkpoint 1

I can recognise and name the 3 logic gates.

Logic Lab

Input A 0

Input B 0

AND GATE

0

2. Mastering Truth Tables

The AND Rule

Output is 1 only if A AND B are 1.

Exam Tip: Inputs always count up in binary: 00, 01, 10, 11.

A	B	Output Q
0	0	?
0	1	?
1	0	?
1	1	?

The OR Rule

Output is 1 if there is a 1 anywhere.

A	B	Output Q
0	0	?
0	1	?
1	0	?
1	1	?

The NOT Rule

Simply flips the input.

A	Output Q
0	?
1	?

The 8-Row Challenge

Complete the table for P = (A AND B) OR C

A	B	C	P
0	0	0	0
0	0	1	1
0	1	0	0
0	1	1	1
1	0	0	0
1	0	1	?
1	1	0	?
1	1	1	?

Checkpoint 2

I can complete truth tables for 2 and 3 inputs.

3. Diagram Bootcamp

Decomposing Questions

"Alarm (Q) sounds if Motion (A) is on AND Armed (B), OR Panic (C) pressed."

Step 1: (Motion AND Armed) -> AND Gate
Step 2: (Result OR Panic) -> OR Gate

Checkpoint 3

I can create diagrams from scenarios.

Final Assessment

1. Which symbol is a NOT gate?

Checkpoint 4

I can use logic to solve problems.