- AQA GCSE Computer Science 8525 (from 2020)
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- Teacher Pack: Unit 3.3 Fundamentals of Data Representation 8525 (from 2020)

## Teacher Pack: Unit 3.3 Fundamentals of Data Representation 8525 (from 2020)

**SKU:**

The resources within this **Teacher Pack** cover all aspects of the specification in relation to AQA GCSE Computer Science 8525 (from 2020) component 3.3.

It includes:

· Teaching PowerPoints (including checkpoint questions and answers) - 125 Slides

· Student PowerPoints (Including checkpoint questions, but omits the answers)

· Homework/Classwork Activities (+ mark schemes)

o Data Capacity

o Conversions

o Compression

· End of unit test (+ mark scheme)

**Content Covered:**

Understand the following number bases:

• decimal (base 10)

• binary (base 2)

• hexadecimal (base 16).

Understand that computers use binary to represent all data and instructions.

Explain why hexadecimal is often used in computer science.

Understand how binary can be used to represent whole numbers.

Understand how hexadecimal can be used to represent whole numbers.

Be able to convert in both directions between:

• binary and decimal

• binary and hexadecimal

• decimal and hexadecimal.

Know that:

• a bit is the fundamental unit of information

• a byte is a group of 8 bits.

Know that quantities of bytes can be described using prefixes. Know the names, symbols and corresponding values for the decimal prefixes: • kilo, 1 kB is 1,000 bytes

• mega, 1 MB is 1,000 kilobytes

• giga, 1 GB is 1,000 Megabytes

• tera, 1 TB is 1,000 Gigabytes.

Be able to compare quantities of bytes using the prefixes above.

Be able to add together up to three binary numbers.

Be able to apply a binary shift to a binary number.

Describe situations where binary shifts can be used.

Understand what a character set is and be able to describe the following character encoding methods:

• 7-bit ASCII

• Unicode.

Understand that character codes are commonly grouped and run in sequence within encoding tables.

Describe the purpose of Unicode and the advantages of Unicode over ASCII. Know that Unicode uses the same codes as ASCII up to 127.

Understand what a pixel is and be able to describe how pixels relate to an image and the

way images are displayed.

Describe the following for bitmaps:

• image size

• colour depth.

Know that the size of a bitmap image is measured in pixels (width x height).

Describe how a bitmap represents an image using pixels and colour depth.

Describe using examples how the number of pixels and colour depth can affect the file size of a bitmap image.

Calculate bitmap image file sizes based on the number of pixels and colour depth.

Convert binary data into a bitmap image.

Convert a bitmap image into binary data.

Understand that sound is analogue and that it must be converted to a digital form for storage

and processing in a computer.

Understand that analogue signals are sampled to create the digital version of sound.

Describe the digital representation of sound in terms of:

• sampling rate

• sample resolution.

Calculate sound file sizes based on the sampling rate and the sample resolution.

Explain what data compression is.

Understand why data may be compressed and that there are different ways to compress data.

Explain how data can be compressed using Huffman coding.

Be able to interpret Huffman trees.

Be able to calculate the number of bits required to store a piece of data compressed using Huffman coding.

Be able to calculate the number of bits required to store a piece of uncompressed data in ASCII.

Explain how data can be compressed using run length encoding (RLE).

Represent data in RLE frequency/data pairs.