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boolean logic

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4 detailed 50-minute lessons with teaching scripts, worked examples, parent guides, and assessment criteria.

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Lesson Overview

Total Lessons: 4
Tier: Foundation and Higher
Duration: 50 minutes per lesson (200 minutes total)
Exam Boards: AQA, Edexcel, OCR, Eduqas, CCEA

Learning Objectives

Prerequisites

Materials & Equipment

Lesson 1: Introduction: boolean logic

Duration: 50 minutes

Starter Activity (5 minutes)

Quick Recall

Write down everything you already know about boolean logic. Then check against the key terms: NOT gate, AND gate, OR gate. Use a mini-whiteboard or paper.

Main Content (35 minutes)

Parent/Teacher Guide:
Before lesson: Read the script below. Pre-teach key vocab: NOT gate, AND gate, OR gate.
If stuck: Re-read the revision notes (link above), then break the content into smaller steps.
Extension: See the Stretch & Challenge ideas in Lesson 4.
Teaching Script (35 mins):
Mins 0-5 - Hook: "Today: boolean logic. By the end you will be able to answer exam questions on it unaided. It connects to the rest of Combined Science (Trilogy) because the ideas here recur across the spec."
Mins 5-20 - Direct Instruction: Work through the core ideas below one at a time; after each, ask your student to explain it back in their own words.
Mins 20-30 - Guided Practice: Model the worked example together, then let your student attempt the first practice question with guidance.
Mins 30-35 - Independent Practice: 2-3 practice questions from Lesson 3 below, with immediate feedback.
First Look

Start with the revision notes summary, then attempt: Draw the truth table for Q = A . B

Plenary (5 minutes)

Check Out

Your student states one thing they learned and one question they still have about boolean logic.

Lesson 2: Core Concepts: boolean logic

Duration: 50 minutes

Starter Activity (5 minutes)

Review Previous Lesson

Quick recap: write 3 key points from Lesson 1 on boolean logic. Check them against the notes below.

Main Content (35 minutes)

Definition: Boolean logic is a form of algebra where all values are either TRUE (1) or FALSE (0). It is named after mathematician George Boole and forms the basis of how computers make decisions.
NOT gate: Takes a single input and produces the opposite (inverted) output. If input is 1, output is 0. If input is 0, output is 1. Also called an inverter.
AND gate: Takes two inputs and outputs 1 (TRUE) only if BOTH inputs are 1. If either or both inputs are 0, the output is 0.
OR gate: Takes two inputs and outputs 1 (TRUE) if EITHER or BOTH inputs are 1. The output is 0 only when both inputs are 0.
XOR gate: Takes two inputs and outputs 1 (TRUE) if the inputs are DIFFERENT. If both inputs are the same (both 0 or both 1), the output is 0. Think of it as "one or the other, but not both."
Key Concept: Logic gates can be combined (cascaded) to create more complex circuits. The output of one gate can become the input of another. Circuits with up to 3 inputs may appear in exams.
TermMeaningExample
01
10
000
010
100
111
000
011

Practice (10 minutes)

Q: Draw the truth table for Q = A . B

Answer: Q = A . NOT B: A=0 B=0 Q=0; A=0 B=1 Q=0; A=1 B=0 Q=1; A=1 B=1 Q=0. Output is 1 only when A=1 AND B=0.

Plenary (5 minutes)

Explain Back

Your student teaches the key points back to you without looking. Fill any gaps immediately.

Lesson 3: Application: boolean logic

Duration: 50 minutes

Starter Activity (5 minutes)

Quick Recall

Recall the key terms: NOT gate, AND gate, OR gate. Define each in one sentence.

Main Content (35 minutes)

Parent/Teacher Guide: Let your student attempt each question alone first, then compare with the model answer. Award method marks for correct working even if the final answer is wrong.

Q1: Draw the truth table for Q = A . B

Answer: Q = A . NOT B: A=0 B=0 Q=0; A=0 B=1 Q=0; A=1 B=0 Q=1; A=1 B=1 Q=0. Output is 1 only when A=1 AND B=0.

Q2: A circuit has the expression Q = (A OR B) AND NOT C. Draw the full truth table.

Answer: Three inputs = 8 rows. Q=1 only when (A=1 OR B=1) AND C=0. Rows where Q=1: (0,1,0), (1,0,0), (1,1,0). All other rows Q=0.

Q3: What is the difference between OR and XOR? Give a real-world example of each.

Answer: OR outputs 1 if either or both inputs are 1. XOR outputs 1 only if the inputs are different. OR example: alarm if front OR back door is open. XOR example: staircase light controlled by two switches - on when switches differ.

Q4: Write the Boolean expression for a circuit where A and B go into an OR gate, and the output is fed into a NOT gate.

Answer: Q = A + B (this is the NOR gate function)

Q5: How many rows does a truth table need for a circuit with 3 inputs?

Answer: 2 3 = 8 rows, covering all combinations from 000 to 111.

Plenary (5 minutes)

Error Review

Review any questions answered incorrectly. Identify whether the error was knowledge, method, or reading the question.

Lesson 4: Exam Practice: boolean logic

Duration: 50 minutes

Starter Activity (5 minutes)

Command Words

Review what these command words require: state (one point), describe (say what happens), explain (say why), compare (both sides), evaluate (judgement).

Main Content (35 minutes)

Extended Answer

Extended question: Full-Mark Response Draw and complete the truth table for the following logic circuit: A AND B is fed into a NOT gate. Then explain what type of gate this combination produces. [4 marks] <div class="

The circuit is: A AND B → NOT = NAND gate A | B | A AND B | NOT (A AND B) 0 | 0 | 0 | 1 0 | 1 | 0 | 1 1 | 0 | 0 | 1 1 | 1 | 1 | 0 This combination produces a NAND gate. The output is 0 only when both inputs are 1, and 1 in all other cases. The NAND gate is the negation of the AND gate — adding a NOT gate to the output of an AND gate produces the NAND truth table.

Exam Tips: Always show intermediate columns in truth tables - marks are awarded for working | Learn the Boolean notation: dot = AND, plus = OR, overbar = NOT | When drawing circuits from expressions, work from the inside out (brackets first) | For 3-input truth tables, count in binary: 000, 001, 010, 011, 100, 101, 110, 111 | Remember order of operations: NOT, then AND, then OR | Practise converting between expressions, circuits, and truth tables in both directions
Common Errors: ✗ Confusing AND, OR, NOT gates with their truth table outputs ✓ AND: output 1 only when ALL inputs are 1. OR: output 1 when ANY input is 1. NOT: output is the opposite of the input. Memorise the truth tables. ✗ Drawing logic gate symbols incorrectly in exams ✓ AND gate: D-shape. OR gate: curved D with curved input side. NOT gate: triangle with circle. Each symbol is distinct — practice drawing them. ✗ Forgetting that a NOT gate can only have ONE input ✓ NOT (inverter) takes exactly one input and produces the opposite. It cannot have two inputs. AND and OR gates can have two or more inputs. ✗ Not recognising that NAND and NOR are the negated versions of AND and OR ✓ NAND = NOT AND (output is
Stretch & Challenge (Grade 8-9):
  • Synoptic links: explain how boolean logic connects to another Combined Science (Trilogy) topic you have studied
  • Real-world: research one real-world use or example of boolean logic
  • Critical: "What are the limitations of the models used in boolean logic?"

Plenary (5 minutes)

Assessment Criteria
  • Got it: Confident explanation + correct worked examples
  • Getting there: Main points OK, needs support with detail
  • Not yet: Confused on key concepts - re-run Lesson 2

Homework & Consolidation

Recommended Resources

🎓 Smart Lesson (Guided)