SS 2 First Term

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

Cognitive	i. Distinguish between RAM and ROM. ii. Describe cache memory and the memory hierarchy. iii. Explain how the processor uses main memory. iv. Explain why a computer uses virtual memory.
Affective	i. Appreciate the value of Main Memory in school, at home and in the community. ii. Show willingness to use digital tools carefully, safely and responsibly.
Psychomotor	i. Draw a table comparing RAM and ROM. ii. Arrange cache, RAM, and storage in order of speed. iii. Explain why cache is placed close to the processor. iv. Describe what happens when RAM is full.

Rationale: Main memory is the primary working memory inside a computer that the CPU accesses directly. Understanding rAM and ROM, cache Memory and the Memory Hierarchy, how the CPU Uses Main Memory helps learners use digital technology confidently, safely and responsibly.

Pre-requisite Knowledge: In Week 1, learners studied Review and Computer Architecture, including review of Computer System and IPO Model, computer Architecture and the CPU, the System Bus and the Fetch-Execute Cycle. 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 Main Memory, 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 2); 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 1 (Review and Computer Architecture) with two quick oral questions, and asks what they already know about Main Memory. Elicits responses and writes the topic on the board.	Recall the previous lesson and share what they already know about Main Memory.	Connecting prior knowledge to Main Memory.
Step 1 8 MINUTES	Covers RAM and ROM: Main memory is the primary working memory inside a computer that the CPU accesses directly. It stores the instructions and data that the CPU is currently working with. Without main memory, the CPU would have no instructions to execute and no data to process.	Listen, take notes and answer oral questions on "RAM and ROM".	Understanding: RAM and ROM.
Step 2 8 MINUTES	Covers Cache Memory and the Memory Hierarchy: Cache memory is very fast, small memory located on or very close to the CPU chip. It stores copies of frequently accessed data and instructions from RAM so that the CPU can retrieve them much faster than going to main memory every time. There are typically three levels of cache.	Copy the key points, give examples from school and everyday life, and ask questions on "Cache Memory and the Memory Hierarchy".	Understanding: Cache Memory and the Memory Hierarchy.
Step 3 8 MINUTES	Covers How the CPU Uses Main Memory: During the fetch-execute cycle, the CPU uses main memory at several points. During the fetch step, the Program Counter sends the address of the next instruction to the MAR, which places it on the address bus. The instruction is then read from RAM into the MDR and placed in the Instruction Register.	Discuss in pairs, then report one point on "How the CPU Uses Main Memory" to the class.	Understanding: How the CPU Uses Main Memory.
Practical Work 6 MINUTES	Guides learners through the practical work: (i) Draw a table comparing RAM and ROM. (ii) Arrange cache, RAM, and storage in order of speed. (iii) Explain why cache is placed close to the processor. 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. Distinguish between RAM and ROM. ii. Describe cache memory and the memory hierarchy. iii. Explain how the processor uses main memory. iv. Explain why a computer uses virtual memory.	Respond verbally and in writing to the evaluation questions.	Assessment and consolidation of the lesson content.
Conclusion 2 MINUTES	Recaps the main points: rAM and ROM, cache Memory and the Memory Hierarchy, how the CPU Uses Main Memory. Links them to the assignment and previews Week 3: Secondary Storage.	Listen, ask questions and copy the assignment.	Reinforcement of key concepts and a preview of the next lesson.

Assignment: i. A computer's CPU is slowed by frequent trips to memory, and its owner notices that only 4 GB of an installed 8 GB is being used. Explain cache memory and the memory hierarchy, and explain the address limit. ii. A computer loses an unsaved document when it is switched off, and it starts up correctly every morning. Explain main memory, RAM and ROM, and state the difference between DRAM and SRAM.