Subject: COMPUTER
Class: JSS 3
Week of the Term: 8th Week
Topic: Construction of Truth Tables
Sub-Topic: Truth Tables for OR, AND, NOT Gates
Objectives
By the end of the lesson, students should be able to:
- Construct truth tables for OR, AND, and NOT gates.
- Analyze how different inputs affect outputs in logic gates.
- Apply truth tables to verify outputs in simple logic circuits.
Entry Behaviour
Students should know basic logic gate functions.
Instructional Materials
- Sample truth tables for each gate.
- Flashcards with different input-output combinations.
- Worksheets for practice.
Reference Materials
- Oyeleke Samson Bukola (2015). Basic Approach to Information Communication Technology for Junior Secondary, Metropolitan Publishers, Lagos.
- Nwabenu M. O., Oyinlola M., Olatunji A. (2010). Basic Science and Technology for Junior Secondary School 3 Textbook (BEC Edition), Spectrum Books Limited, Lagos.
Content
Understanding Truth Tables
Truth tables are a fundamental tool in digital logic design that outline the relationship between inputs and outputs for logical operations. They provide a systematic way to display all possible input combinations for a particular logical function and the corresponding outputs.
Key Logic Gates and Their Truth Tables
Three basic logic gates: AND, OR, and NOT. Each gate has its own unique behavior, and understanding these will help students create and interpret truth tables effectively.
- AND Gate
- Symbol: A flat-ended shape.
- Function: The output is true (1) only if all inputs are true (1).
- Truth Table:
| A | B | Output (A AND B) |
|---|---|---|
| 0 | 0 | 0 |
| 0 | 1 | 0 |
| 1 | 0 | 0 |
| 1 | 1 | 1 |
- Example: If A represents “It is sunny” and B represents “I have an umbrella,” the output (A AND B) would be “I can go outside” only when both conditions are true.
- OR Gate
- Symbol: A curved shape with a point at the end.
- Function: The output is true (1) if at least one input is true (1).
- Truth Table:
| A | B | Output (A OR B) |
|---|---|---|
| 0 | 0 | 0 |
| 0 | 1 | 1 |
| 1 | 0 | 1 |
| 1 | 1 | 1 |
- Example: If A represents “I have pizza” and B represents “I have ice cream,” the output (A OR B) means “I have dessert” is true if I have either pizza or ice cream or both.
- NOT Gate
- Symbol: A triangle pointing to a circle.
- Function: The output is the inverse of the input; if the input is true (1), the output is false (0), and vice versa.
- Truth Table:
| A | Output (NOT A) |
|---|---|
| 0 | 1 |
| 1 | 0 |
- Example: If A represents “It is raining,” then NOT A indicates “It is not raining.”
Step 1: Introduction
Lesson Presentation (Step-by-Step Procedure)
Others removed.
