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Lesson 1:

Across time and space

Year 8 – Data Representations – Representations: from clay to silicon

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Discuss

Starter activity

Why do you think people invented writing?

Have the question “Why do you think people invented writing?” displayed on a slide as learners enter the classroom. Ask them to contemplate this question.

Ask the learners to offer possible answers. Write them on the board without commentary. You will return to these responses and comment on them or highlight them at the end of Activity 1, while reflecting on the question “Why do you think people needed to write that down?”. (These questions are essentially identical.)

Answers might relate to storing information, or communicating. Writing things down is also necessary for performing non-trivial computations, i.e. information processing, but this is unlikely to come up at this point.

Note: Learners might find this a strange question and enquire what it has to do with computing. You could explain that writing is a way to represent information, and humans invented writing to solve certain kinds of problems. By examining the ways in which humans represent information, we can build an understanding of how computers represent information and how they help us solve these problems.

Image source:

https://commons.wikimedia.org/wiki/Category:Linear_B_tablets#/media/File:Clay_Tablet_inscribed_with_Linear_B_script.jpg

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In this lesson, we will...

Objectives

Uncover the problems we solve through writing.

Discover how Computing is also about solving these problems.

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Museum visit

Activity 1

Examine the exhibits.

There are different types of representations.

There are different types of information.

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Think, write, pair, share

Activity 1

Why do you think people needed to write that information down?

Accounts and inventories

History, poetry, and literature

Magic spells

Laws and contracts

Astronomical observations

Mathematics

Music

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Think, write, pair, share

Activity 1

Why do you think people needed to write that information down?

Share your answers with the rest of the class.

Accounts and inventories

History, poetry, and literature

Magic spells

Laws and contracts

Astronomical observations

Mathematics

Music

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Reflection

— link to Computing

Activity 1

Why do you think people needed to write that information down?

To store it (across time)

To communicate (across distance)

To process it

Sequences of symbols can represent any piece of information.

Computers need to store, process, and communicate information.

Computers use sequences of symbols to represent information.

Your summary of the answers should guide learners towards the general takeaway that writing, i.e. representing information with sequences of symbols, is necessary for storing, exchanging, and processing information. Learners need to realise how important these three functions have been to humans, and how using representations has been a fundamental step in solving these kinds of problems.

Note that the images in this activity deliberately contain a very broad range of topics, which should convey the idea that any piece of information can be represented using such sequences of symbols. This is something that you may want to stress during your discussion.

Make an explicit link to how all of this relates to Computing: since computers are machines that store, exchange, and process information, it is necessary for them to use sequences of symbols to represent this information. Computers are simply the tool that allows humans to automate the storage, processing, and transmission of information.

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Choosing representations

Activity 2

Who decides on what these sequences of symbols mean?

In which situation would each representation be used?

Here are a few additional examples of sequences of symbols, which represent information.

Write your answers on your worksheet.

Inform learners that they will now be presented with additional examples of sequences of symbols, which represent information.

Start with the images from the previous activity, followed by examples of contemporary representations, and ask learners to do a ‘think, write, pair, share’ activity on the following questions: “Who decides on what these sequences of symbols mean? Why would we use one representation instead of another?”

Again, make sure that learners write their answers down on the worksheet before they pair and share.

The first few examples, flag semaphores, sign language, and braille, are likely to be familiar and are all used for communication between humans. Go over each image and ask the learners if they are indeed familiar, and provide an explanation if this is not the case.

The examples are primarily meant to illustrate that representations are selected so that they are effective for the task and medium at hand. The final example doesn’t pertain to communication between humans. It contains familiar representations that are meant to be readable by machines. Again, the representation is chosen to be effective for the task and medium at hand. Discussing machine-readable representations will provide a convenient bridge into the representations used in digital devices.

Image sources:

https://en.wikipedia.org/wiki/Acta_Eruditorum#/media/File:Acta2.jpg

https://commons.wikimedia.org/wiki/Category:Flag_semaphore#/media/File:020118-N-6520M-011_Semaphore_Flags.jpg

https://www.british-sign.co.uk/print-a-word-in-fingerspelling/

https://commons.wikimedia.org/wiki/Category:Sign_languages#/media/File:El_Ayuntamiento_de_Madrid_apuesta_por_un_San_Isidro_inclusivo_y_accesible_01.jpg

https://github.com/LazoCoder/Braille-Translator

https://commons.wikimedia.org/wiki/Category:Braille#/media/File:A_person_reading_a_braille_book.jpg

Bar codes for representing product codes: https://en.wikipedia.org/wiki/Barcode#/media/File:EAN-13-5901234123457.svg

QR codes for representing any kind of text, usually URLs (web addresses): https://en.wikipedia.org/wiki/Barcode#/media/File:QR_code_for_mobile_English_Wikipedia.svg

Codes used by Royal Mail to represent addresses: https://en.wikipedia.org/wiki/Barcode#/media/File:Royal_Mail_mailmark_C_barcode.png

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Choosing representations

— link to Computing

Activity 2

Who decides on what these sequences of symbols mean?

We (humans) agree on meaning.

In which situation would each representation be used?

Different representations may be suitable for different situations.

Information in computers must be represented in a form convenient for processing.

Share your answers with the rest of the class.

When the allocated time is over, start by discussing the learners’ answers to the question “Who decides on what these sequences of symbols mean?”. This should be straightforward to answer (even though the learners may have not asked themselves this question before): humans develop these representations themselves and, over time, they come to agree on their interpretation and meaning. There’s no inherent meaning to these representations; it’s all about conventions.

Then, discuss the learners’ answers to the question “Why would we use one representation instead of another?” and summarise them.

Your summary of the answers should guide learners towards the general takeaway that representations are selected so that they are effective for the task and medium at hand.

Again, make an explicit link to Computing, which should follow from the previous discussion: “Information in computers must be represented in a form convenient for computer processing.” At this point, you could informally ask the learners if they are familiar with the symbols that computers use to represent information.

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Meanings

Activity 3

Different sequences of symbols can represent the same thing.

Example:

symbol

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Meanings

Activity 3

The same sequence of symbols can represent different things.

Example:

dab

a kind of fish

a sudden blow or thrust

a gentle touch or stroke

a small amount

a skillful person

a dance move

the musical notes D, A and B

the number 3499

Digital Audio Broadcasting

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Lesson takeaways

Activity 4

Write your lesson takeaways on a sticky note.

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Lesson takeaways

Activity 4

We invented writing to store information.

Computers use symbols to represent information too.

Some representations are more convenient than others.

Patterns of symbols can mean anything that we agree they can.

We use symbols to communicate.

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Next lesson

Summary

In this lesson, we...

Examined how symbols can be used to store, communicate, and process information.

Next lesson, we will...

Use paper, lights, and drums to send and receive messages.