SS 2 First Term

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

Cognitive	i. Explain place value in the decimal, binary, octal and hexadecimal systems. ii. Convert numbers between decimal, binary and hexadecimal. iii. Explain how characters, images and sound are represented. iv. Use the units that measure file sizes.
Affective	i. Appreciate the value of Number Systems and Data Representation in school, at home and in the community. ii. Show willingness to use digital tools carefully, safely and responsibly.
Psychomotor	i. Convert the decimal number 45 to binary and to hexadecimal. ii. Write the ASCII code for the letter A in binary. iii. Explain how a colour image is stored using pixels. iv. Arrange bit, byte, kilobyte, megabyte and gigabyte in order.

Rationale: A number system is a way of writing numbers using a fixed set of symbols called digits and a base (the radix). Understanding understanding Number Systems, binary Number System, converting Decimal to Binary, octal Number System helps learners use digital technology confidently, safely and responsibly.

Pre-requisite Knowledge: In Week 4, learners studied Operating Systems, Software Licensing and Applications, including types of Operating Systems, common Operating Systems, functions of an Operating System. 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 Number Systems and Data Representation, 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 5); 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 4 (Operating Systems, Software Licensing and Applications) with two quick oral questions, and asks what they already know about Number Systems and Data Representation. Elicits responses and writes the topic on the board.	Recall the previous lesson and share what they already know about Number Systems and Data Representation.	Connecting prior knowledge to Number Systems and Data Representation.
Step 1 6 MINUTES	Covers Understanding Number Systems: A number system is a way of writing numbers using a fixed set of symbols called digits and a base (the radix). Covers Binary Number System: Binary uses only the digits 0 and 1, and each position is worth a power of 2, working from the right, namely 1, 2, 4, 8, 16, 32, 64, 128. Covers Converting Decimal to Binary: To convert decimal to binary, divide the number repeatedly by 2, write down the remainder each time and stop when the quotient becomes 0, then read the remainders from bottom to top. Also covers Octal Number System.	Listen, take notes and answer oral questions on "Understanding Number Systems" and related points.	Understanding: Understanding Number Systems; Binary Number System; Converting Decimal to Binary; and related ideas.
Step 2 6 MINUTES	Covers Hexadecimal Number System: Hexadecimal uses the digits 0 to 9 and the letters A to F, where A = 10, B = 11, C = 12, D = 13, E = 14 and F = 15. Covers ASCII and Character Codes: A computer does not store letters directly; it stores numbers. Covers Unicode: ASCII can only cover English and a few symbols, so Unicode gives a unique number to every character in every writing system, over 140,000 characters today, including Yoruba, Hausa, Igbo, Arabic, Chinese and emoji. Also covers Representing Images.	Copy the key points, give examples from school and everyday life, and ask questions on "Hexadecimal Number System" and related points.	Understanding: Hexadecimal Number System; ASCII and Character Codes; Unicode; and related ideas.
Step 3 6 MINUTES	Covers Representing Sound: Sound is captured by sampling the wave many times per second. Covers Representing Video: Video stores a sequence of frames and displays a new one at every frame rate, usually 24 to 30 per second. Covers Measuring File Sizes: Digital data is measured in bits and bytes. Also covers Practical Exercises.	Discuss in pairs, then report one point on "Representing Sound" and related points to the class.	Understanding: Representing Sound; Representing Video; Measuring File Sizes; and related ideas.
Step 4 6 MINUTES	Covers How Computers Represent Data: A computer represents all data using a fixed-length binary pattern. Covers Number Conversions with Worked Examples: Converting between number systems follows two systematic methods. Covers Representing Characters, Images, Pixels and Colour Depth: Beyond ASCII and Unicode, computers also encode images as binary data.	Respond to questions, complete the examples on the board and note down "How Computers Represent Data" and related points.	Understanding: How Computers Represent Data; Number Conversions with Worked Examples; Representing Characters, Images, Pixels and Colour Depth.
Practical Work 6 MINUTES	Guides learners through the practical work: (i) Convert the decimal number 45 to binary and to hexadecimal. (ii) Write the ASCII code for the letter A in binary. (iii) Explain how a colour image is stored using pixels. 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 place value in the decimal, binary, octal and hexadecimal systems. ii. Convert numbers between decimal, binary and hexadecimal. iii. Explain how characters, images and sound are represented. iv. Use the units that measure file sizes.	Respond verbally and in writing to the evaluation questions.	Assessment and consolidation of the lesson content.
Conclusion 2 MINUTES	Recaps the main points: understanding Number Systems, binary Number System, converting Decimal to Binary, octal Number System, hexadecimal Number System. Links them to the assignment and previews Week 6: Logic Gates and Digital Logic.	Listen, ask questions and copy the assignment.	Reinforcement of key concepts and a preview of the next lesson.

Assignment: i. A student is asked to convert the binary number 1101 to decimal. Show the conversion step by step and give the answer. ii. A web designer writes a colour as #FF5733 instead of a long run of binary digits. Explain why hexadecimal is more compact than binary for such codes, and calculate the decimal value of the first pair, FF, to show that two hex digits represent one byte (8 bits).