Level 4 Binary

Topic: L4 – Binary Addition
Subject: Computer Systems and Networks

The lesson begins by revisiting how number systems work, then builds students towards being able to perform binary addition.

Learning objectives

By the end of the lesson, students should be able to:

Add two binary numbers, each less than 7 bits.
Multiply a binary number by 2.
Identify whether a binary number is odd or even.
Lesson sequence

1. Starter / retrieval
   The lesson begins with a starter before moving into the core content.

2. Decimal/denary recap
   Students revisit the denary number system and place value. For example, 583 = 500 + 80 + 3, reinforcing the idea that each place is worth ten times the previous place.

3. Why computers use binary
   The lesson then connects binary to computer hardware: electronic circuits and switches have two states — On and Off, represented by 1 and 0.

4. Binary representation
   Students explore how binary place values work:

1, 2, 4, 8, 16, 32, 64, 128

They also investigate how increasing the number of switches/bits increases the number of possible combinations, from 2 combinations with one switch to 256 with eight.

1. Binary ↔ denary conversion
   Students practise converting:

Binary → denary
Denary → binary

For example, the lesson demonstrates 1101 = 13 and later converts 28 into binary.

Students then complete Worksheet 4.1, with separate challenges for the two conversion directions.

1. Odd and even numbers
   The lesson introduces a useful binary pattern: the right-hand bit determines whether the number is odd or even.

Ends in 1 → odd
Ends in 0 → even

Students then identify whether several binary numbers are odd or even.

1. Multiplying binary by 2
   Students discover that adding a zero to the right of a binary number doubles its value:

1011 = 11
10110 = 22

They then try the same with another example.

1. Denary addition recap
   Before binary addition, the lesson briefly revisits the familiar process of decimal addition, including carrying.

2. Binary addition
   This is the main new learning. Students are introduced to the five binary addition rules:

0 + 0 = 0
0 + 1 = 1
1 + 0 = 1
1 + 1 = 0, carry 1
1 + 1 + 1 = 1, carry 1

Students then apply these rules to add binary numbers, working right to left and managing the carry bit.

1. Independent practice
   Students complete Worksheet 4.2, practising binary/decimal conversions and the arithmetic skills from the lesson.

2. Plenary / self-assessment
   The lesson finishes by asking students to assess whether they can:

Add two binary numbers.
Multiply binary by 2.
Identify odd/even binary numbers.
Identify and explain the key vocabulary.