# 2.1.4 Representation of data in computer systems

# Units

# Number

### Binary Tetris

Binary Tetris is a flash game designed to help teach students the binary number system. Players must flip bits to achieve the required number, or add up the bits to calculate the number being represented. I'd recommend asking students to turn their sound off before starting this!

*Updated: 2015-04-07*

### Hexadecimal-binary matching game

This is a fun little matching pairs style game in which players must match decimal numbers with their hexadecimal equivalents. A good way of testing students' ability to quickly perform mental conversions. Click here to play.

*Updated: 2017-11-05*

### Introducing Binary

The new-look BBC Bitesize site have extensive notes on binary numbers, with clear diagrams and examples of how they work and how they can be added. Several videos brighten up the content and key concepts are related to real-life situations - such as CPU word size. Later pages of the notes cover conversion between different number bases. The site also features short multiple-choice quizes to test students' understanding of the key concepts.

*Updated: 2015-04-15*

### Binary conversion activities

These two worksheets help students with decimal to binary conversion and vice versa. The activities were created by Gary Kacmarcik at the Computer Science & Engineering for K-12 site and are licensed under the Creative Commons Attribution-Share Alike 3.0 license.

*Updated: 2015-04-15*

### Binary crossword activities

These two puzzles are a great way to test students' hexadecimal to binary conversion skills. They work much like a normal crossword, except that the clues are written in hexadecimal and the answers must be written in binary. Once complete, the crosswords make simple bitmap images if the 1s are shaded and the zeroes left blank. You can download puzzle 1 (answers) and puzzle 2 (answers).

These puzzles were created by Gary Kacmarcik at the Computer Science & Engineering for K-12 site - an excellent site which I recommend you visit. They are licensed under the Creative Commons Attribution-Share Alike 3.0 license.

*Updated: 2015-04-15*

### Binary to hexadecimal

A worksheet that explains the "divide into groups of 4" method of converting binary numbers to hexadecimal numbers.

This was created by Gary Kacmarcik at the Computer Science & Engineering for K-12 site - an excellent site which I recommend you visit. They are licensed under the Creative Commons Attribution-Share Alike 3.0 license.

*Updated: 2015-04-16*

### Lesson - Data representation - binary

This download contains all lesson resources necessary to teach students binary. It includes explanations of the system and lesson activities.

This lesson is one of the many excellent resources provided under CC-NC-SA by Mr Colley.

*Updated: 2017-10-15*

### Lesson - Data representation - hexadecimal

This download contains all lesson resources necessary to teach students base 16 (hexadecimal). It includes PowerPoint presentations that cover the number system and converting to denary and binary. There are also some nice hex table handouts for students who may be struggling to grasp the concepts. how sound is represented in binary.

This lesson is one of the many excellent resources provided under CC-NC-SA by Mr Colley. I've added PDF versions of the .pub versions found in the original download, for those who don't have Microsoft Publisher.

*Updated: 2017-10-15*

### Counting in binary

This handy PDF serves as a good summary sheet for students learning to count in binary. It covers decimal numbers from 0 to 63 (5 bits). It is good for GCSE and younger students, although it can be useful for older students too.

The sheet was created by Gary Kacmarcik at the excellent cse4k12 site and is licensed under the Creative Commons Attribution-Share Alike 3.0 Unported License.

*Updated: 2017-10-17*

### Counting in hex

Similar to the binary sheet, this handy document covers decimal numbers 0 to 63. It is useful for teaching students who are new to binary, or as a quick recap for those revising it. The sheet was created by Gary Kacmarcik at the excellent cse4k12 site and is licensed under the Creative Commons Attribution-Share Alike 3.0 Unported License.

*Updated: 2017-10-17*

### Binary and Hexadecimal starter activities

Two lesson starter, plenary, or homework activities are the binary crossword and the matching quiz. They test students' ability to read binary and hexadecimal, and convert between these systems and denary.

*Updated: 2017-10-17*

# Character

### Lesson - Data representation - text

This download contains all lesson resources necessary to teach students how ASCII is used to representation text in a computer system. The download includes several fun activities where students have to uncover 'secret' messages using their understanding of binary and ASCII. There are different worksheets for students of different levels.

This lesson is one of the many excellent resources provided under CC-NC-SA by Mr Colley.

*Updated: 2017-10-15*

### Text representation worksheets

Gary Kacmarcik at the excellent cse4k12 site has created a set of sheets for a lesson activity on text representation. The first sheet is an ASCII table and the other two sheets ask students to encode a text message and decode a message respectively. Note that students are expected to encode and decode using hexadecimal rather than binary (although they could easily be asked to use binary instead).

*Updated: 2017-10-17*

### CS Field Guide - Data representation

CS Field Guide is an absolutely fantastic resource filled with material that is well written, clear,and accessible. Each section comes with highlighted key points, extension points, and even interactives to help understand the concepts. The interactives are excellent as teaching resources (many of them are linked here), while the notes themselves make excellent revision resources - particularly for GCSE.

This section covers all aspects of data representation - numbers, text, images, and instructions.

*Updated: 2017-10-24*

# Images

### B&W Pixelation

There are three versions of this excellent applet, designed for the University of Chicago's Introduction to Computer Science course to help students understand image representation in computers. In the first version, students simply enter binary digits to represent black or white pixels. In the second version students are introduced to the concept of a very basic file format, with the first two bytes representing the image dimensions. Students can also enter the data in binary or hexadecimal. The final version is even more complex, allowing students to specify the colour depth of the image, and requiring them to enter the appropriate number of bits for each pixel.

Overall this site is an excellent introduction to data storage and image representation, and makes a complex subject quite entertaining.

*Updated: 2015-04-09*

### Image Representation - Flash activity

This Flash activity lets students draw a simple bitmap image and represents it using a simple run-length encoding (RLE) algorithm in real time. Students can also important text representations of the compressed data and the application will draw the corresponding image. The web page is not in English but the application is still perfectly usable.

*Updated: 2015-04-15*

### Hexadecimal colour codes

Section 5.5.2 of this much bigger page on data representation covers the uses of hexadecimal numbers to represent colours in images. It explains the correlation between the hexadecimal digits and the number of bits available, and the effect the bit depth has on the appearance of the image. The excellent interactives really make the concept come alive and visually highlight these differences to students. A highly recommended resource.

*Updated: 2015-06-03*

# Sound

### Lesson - Data representation - sound

This download contains all lesson resources necessary to teach students how sound is represented in binary. It includes PowerPoint presentations, worksheets, and sample sounds for students to play.

This lesson is one of the many excellent resources provided under CC-NC-SA by Mr Colley.

*Updated: 2017-10-15*