SS 2 First Term

LEARNING OBJECTIVES: BY THE END OF THE LESSON STUDENTS SHOULD BE ABLE TO:

Cognitive	i. Explain what a logic gate is and how it uses bits. ii. Draw truth tables for the AND, OR and NOT gates. iii. Describe the NAND, NOR, XOR and XNOR gates. iv. Explain the use of Boolean algebra and adders.
Affective	i. Appreciate the value of Logic Gates and Digital Logic in school, at home and in the community. ii. Show willingness to use digital tools carefully, safely and responsibly.
Psychomotor	i. Draw the truth tables for AND, OR and NOT. ii. Write the truth table for the NAND gate. iii. Explain how a half adder adds two bits. iv. Simplify a simple Boolean expression.

Rationale: A logic gate is a tiny circuit that takes one or more binary inputs, each a 0 or a 1, and produces a single binary output according to a fixed logical rule. Understanding what is a Logic Gate?, the AND Gate, the OR Gate, the NOT Gate helps learners use digital technology confidently, safely and responsibly.

Pre-requisite Knowledge: In Week 5, learners studied Number Systems and Data Representation, including understanding Number Systems, binary Number System, converting Decimal to Binary. The knowledge from that week is used again in this lesson.

Learning Material/Teaching Aid: Whiteboard, markers, computer or laptop where available, printed notes and charts on Logic Gates and Digital Logic, practical task sheets, learners' notebooks and pens.

Reference Materials: Digital Technology for Senior Secondary Schools (SS 2); NERDC Digital Technology Curriculum; Digital Technology SS 2 First Term Notes (Week 6); First Term examination and Continuous Assessment question papers.

LESSON DEVELOPMENT

Stage/Step (Time)	Teacher's Activities	Student's Activities	Learning Points
Introduction 5 MINUTES	Welcomes learners, revises Week 5 (Number Systems and Data Representation) with two quick oral questions, and asks what they already know about Logic Gates and Digital Logic. Elicits responses and writes the topic on the board.	Recall the previous lesson and share what they already know about Logic Gates and Digital Logic.	Connecting prior knowledge to Logic Gates and Digital Logic.
Step 1 6 MINUTES	Covers What is a Logic Gate?: A logic gate is a tiny circuit that takes one or more binary inputs, each a 0 or a 1, and produces a single binary output according to a fixed logical rule. Covers The AND Gate: An AND gate has two or more inputs and its output is 1 only when all inputs are 1; if any input is 0, the output is 0. Covers The OR Gate: An OR gate outputs 1 when at least one input is 1, and 0 only when all inputs are 0. Also covers The NOT Gate.	Listen, take notes and answer oral questions on "What is a Logic Gate?" and related points.	Understanding: What is a Logic Gate?; The AND Gate; The OR Gate; and related ideas.
Step 2 6 MINUTES	Covers The NAND and NOR Gates: NAND stands for NOT AND, which is an AND gate followed by an inverter, so its output is 0 only when all inputs are 1 and 1 in every other case; the expression is NOT (A AND B). Covers The XOR and XNOR Gates: XOR stands for exclusive OR. Covers Boolean Algebra: Boolean algebra is the mathematics of 0 and 1. Also covers De Morgan's Laws.	Copy the key points, give examples from school and everyday life, and ask questions on "The NAND and NOR Gates" and related points.	Understanding: The NAND and NOR Gates; The XOR and XNOR Gates; Boolean Algebra; and related ideas.
Step 3 6 MINUTES	Covers The Half Adder: Combinational logic is a circuit whose output depends only on the present inputs, with no memory. Covers The Full Adder: A half adder cannot handle a carry from a previous column, so real arithmetic uses a full adder with three inputs, namely A, B and a carry-in (Cin). Covers Applications of Logic Gates: Logic gates appear throughout a computer. Also covers Practical Exercises.	Discuss in pairs, then report one point on "The Half Adder" and related points to the class.	Understanding: The Half Adder; The Full Adder; Applications of Logic Gates; and related ideas.
Step 4 6 MINUTES	Covers Digital Logic and Binary Signals: Digital logic is the branch of electronics that processes binary information, signals that are either 0 or 1, low or high. Covers Gate Functions and Truth Tables at a Glance: The six gates can be grouped by how they behave. Covers Combining Gates to Build Simple Circuits: Few real systems use a single gate. Also covers Real-World Applications of Logic Circuits.	Respond to questions, complete the examples on the board and note down "Digital Logic and Binary Signals" and related points.	Understanding: Digital Logic and Binary Signals; Gate Functions and Truth Tables at a Glance; Combining Gates to Build Simple Circuits; and related ideas.
Practical Work 6 MINUTES	Guides learners through the practical work: (i) Draw the truth tables for AND, OR and NOT. (ii) Write the truth table for the NAND gate. (iii) Explain how a half adder adds two bits. Moves round the class to check progress and correct unsafe or careless use.	Carry out the practical tasks individually or in pairs and record what they did in their notebooks.	Applying the lesson through hands-on practice.
Evaluation 3 MINUTES	Asks learners to: i. Explain what a logic gate is and how it uses bits. ii. Draw truth tables for the AND, OR and NOT gates. iii. Describe the NAND, NOR, XOR and XNOR gates. iv. Explain the use of Boolean algebra and adders.	Respond verbally and in writing to the evaluation questions.	Assessment and consolidation of the lesson content.
Conclusion 2 MINUTES	Recaps the main points: what is a Logic Gate, the AND Gate, the OR Gate, the NOT Gate, the NAND and NOR Gates. Links them to the assignment and previews Week 7: Computer Networks.	Listen, ask questions and copy the assignment.	Reinforcement of key concepts and a preview of the next lesson.

Assignment: i. A student builds a circuit with two switches wired so a lamp turns on only when both switches are closed. Identify the logic gate that models this circuit and draw its truth table. ii. An engineer needs a gate that outputs 0 only when both inputs are 1. Identify the gate, write its Boolean expression and explain why NAND gates are called universal gates.