Binary Lesson 1

• Computing
• Lower Secondary (Key Stage 3)

Binary Basics: Understanding Numbers in Computing

Do now: Can you count to 31 one hand?

How could you do it?

Learning Objectives

Aspire: Understand the purpose of denary and binary, 

Conquer: interpret the binary number line and convert between denary and binary.

What is Denary?

Denary, or decimal, is called a base-10 number system. 

• It uses the digits 0-9. It's the most common system for everyday counting and arithmetic

• We use 0-9 to make every other number that exists.
• 127
• 1024

What is Binary?

Binary is a base-2 number system. It uses only two digits:

• What could those digits be? 

• Hint: Computers run on electricity. electricity can only be on or off

What is Binary?

Binary is a base-2 number system. It uses only two digits: 

• We use 1 and 0 in binary.

• 1 means on and 0 means off.

• These are the only 2 numbers we are allowed to use. 

Which of these is an example of a denary number?

1. 1010101
2. 101010101
3. 01010101
4. 127

Which 2 numbers do we use in binary?

1. 1 and 2
2. 9 and 10
3. 0 and 1
4. 5 and 6

What digits to denary numbers use

1. 1 and 2
2. 0 to 9
3. 10 to 20
4. 1 to 10

Binary Number Line

The binary number line is very different to how we normally count. 

• Here is the full binary number line. 

• You can see we double each time we move forward. 

How do we change denary numbers to binary?

Computers do not understand the numbers we use, they have to be changed so the computer can understand them. 

Pre-watch the video to help. the students will then have a go at some simple conversions. 

Complete questions 1 to 5

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Teams

What is the number 2 in binary?

1. 0001
2. 0010
3. 1111
4. 0000

What is the number 15 in binary?

1. 0001
2. 0010
3. 1111
4. 0000

What is the number 12 in binary?

1. 1100
2. 0001
3. 1111
4. 0011

Why do we convert into binary?

1. To shorten the number
2. Its the only way the computer can understand numbers.
3. To test our skills.
4. To save time.

Converting back

The computer will also convert the numbers back again on our screens so we can understand them. 

Complete questions 6 to 10

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Teams

Larger number 

Computers have to deal with very large numbers all of the time. so we extend the number line by doubling the numbers. 

Extension: 

Complete questions 11 to 15

Binary bulbs 

Click here

If need a game on the board for conversion, to could use this to test knowledge, award points, ask kids to come up to the board, or play by themselves.