Learning outcomes
Students will be able to:
Key question
 How can you create a play to teach someone how binary works, without using the binary cards?
Lesson starter
Notes on resources
The classroom resources we suggested are highly motivating, however please use any resources you have available in your classroom that have two different states, sounds or sizes.
Computers use on and off to know how to display information or data.
We can use anything we like that is opposite to each other.
Today we will look at what opposites are and how we can count using these.
If I said “happy face” what would be the opposite?
What would the opposite be of cat? (This could be a mouse or a dog).
Introduce two opposite objects.
They could be paper plates, dual coloured counters, hats (to put on or off), or two different percussion instruments.
Your play must include a demonstration of one of the following:
 How to count from 0 to 10 or more using binary dots.
 How you would work out the number 5.
Lesson activities
Brainstorm together items you could use to make the numbers.
It should be different to how it has been demonstrated to the class, so they are not allowed to use cards with dots on them.
In groups of 4 have students decide how they will show ON and OFF.
They need to choose which bit they are going to be.
(It may help to give them each their own bit card so they remember their number).
As well as physical representations like hats, it could be using words (e.g. saying "yes and no"), or musical sounds (high and low, long and short, loud and soft), or light.
8, 4, 2, 1
Have a chance to practise counting in their group from 1 to 8.
Once they have done that they change roles to they experience what it's like being each of the different bits:
 The person with 8 takes on the job of 1
 4 becomes 8
 2 becomes 4
 1 becomes 2
When they are ready ask each group to make the number (choose a random number between 0 and 8).
Your plays will typically need 4 students in a group to represent the four bits.
If the number of students isn't a multiple of 4, the extra students could take on roles such as taking photos or videos.
The roles can swap over so they have a turn at being a “bit” as well as capturing the learning.
Alternatively, a smaller group could explore other options, such as one student holding two bits, or using objects as bits on 4 chairs "operated" by the students, so one student can change all of them.
Teaching observations
The number pattern is from highest to lowest, left to right (it's just a convention, but we use the same one in the decimal number system, with the most significant digits on the left):
8, 4, 2, 1
Therefore watch that they haven’t switched the order of the place values, for example they check they aren’t representing the decimal number 1 as:
1, 0, 0, 0 (which actually represents the decimal number 8)
Below is an example of where students believed that 3 in decimal is represented as 0100, as they focused on the pattern of numbers rather than using the place values.
0001
0010
0100 (where it should be 00011 for 3)
Applying what we have just learnt
Reflect after each play is performed to reinforce learning by asking:

How did they choose to show on and off?

What made the plays interesting or appealing that another person might be able to learn from them?
Lesson reflection

What did you clarify about the binary number system now that you’ve created your play?

What questions do you have after performing your play in relation to the binary number system? (
Typically responses are that they want to understand further how binary numbers are used to show letters, images, videos and all things on a computer  these topics are covered in further lesson plans)
Seeing the Computational Thinking connections
Throughout the lessons there are links to computational thinking. Below we've noted some general links that apply to this content.
Teaching computational thinking through CSUnplugged activities supports students to learn how to describe a problem, identify what are the important details they need to solve this problem, break it down into small logical steps so that they can then create a process which solves the problem, and then evaluate this process. These skills are transferable to any other curriculum area, but are particularly relevant to developing digital systems and solving problems using the capabilities of computers.
These Computational Thinking concepts are all connected to each other and support each other, but it’s important to note that not all aspects of Computational Thinking happen in every unit or lesson. We’ve highlighted the important connections for you to observe your students in action. For more background information on what our definition of Computational Thinking is see our notes about computational thinking.
This lesson supports students to apply and recognise the computational thinking links from lesson one.
Explicit links could include:
Algorithms
Examples of what you could look for:
Do students demonstrate how the binary number system works by explaining, systematically, what is happening to work out the binary representation of a given number?
Abstraction
Examples of what you could look for:
Ask students to look at a demonstration created by other students and list the features of the objects used that are important to demonstrate the binary number system and those that aren’t relevant at all. e.g. using teddy bears  having the back or front showing is important, the colour of the teddy isn’t important, the size of the teddy isn’t important.
Decomposition
Examples of what you could look for:
Watch a demonstration and ask students to point out some of the small steps that the students in the demonstration had to do e.g. this could be when a single bit out of a group is determined to be on or off.
Generalising and patterns
Examples of what you could look for:
Have students review three demonstrations and ask what do these each had in common and what was different about them.
Ask them if they notice any patterns while they are counting.
Evaluation
Examples of what you could look for:
Have students consider the number of bits used in each demonstration, and the difference this makes in the range of values that can be represented.
Logic
Examples of what you could look for:
Finding errors or misconceptions in the demonstrations can exercise students logical reasoning.