It includes:

~~Student Learning Record Workbook (for use by students)~~- Student Learning Record Answers (for use by teachers)
- End of Topic test and answers
- Lesson PowerPoint’s for every lesson
- Any associated answers or references sheets for class activities

This topic covers:

- 3.3.1 – 3.3.8 from the specification (8525)

3.3.1 Number bases

- 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.

3.3.2 Converting between number bases

- 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

3.3.3 Units of information

- 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.

3.3.4 Binary arithmetic

- 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.

3.3.5 Character encoding

- 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.

3.3.6 Representing images

- 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.

3.3.7 Representing sound

- 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.

3.3.8 Data compression

- 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.