# 2.2 Data representation

# 2.2.1 Data Types

### Characters, Symbols and the Unicode Miracle

Characters, Symbols and the Unicode Miracle explains how ASCII arose from the need to communicate data in a compatible manner between computer systems, and the problems that arise with this apparently simple task. It then discusses the creation of the Unicode system.

*Updated: 2015-04-29*

### Unicode Table

Unicode table is a nice scrollable web page which lists all of the unicode characters. The title and a brief description of each section is presented while you scroll. This page is useful for helping students realise just how many different characters need to be represented by computer systems, and the problems this would cause with a standard like Unicode.

*Updated: 2015-04-29*

# 2.2.2 Arrays

### VisuAlgo: Sorting Algorithms

Visu Algo is another site which offers animated visualizations of common computing algorithms. The great thing about their animated sorting algorithms is the ability to display pseudo-code next to the animation and have it run step-by-step, following each line of code as it is processed. Really useful for helping students better understand code.

*Updated: 2015-04-13*

### Bubble sort and Merge sort

Using a combination of playing cards and simple computer animations, this video clearly explains the bubble sort and merge sort algorithms step by step. It also compares the speed of each algorithm of data sets of different sizes.

The second half of the video examines the complexity of the algorithms, introducing 'Big O' notation and highlighting how bubble sort's complexity is a major drawback on large lists.

*Updated: 2015-05-27*

### The Sorting Balance

This is another interactive to help students learn about sorting algorithms. They must use a set of virtual scales to test and compare the weights of 10 jars. Students must then line the jars up in the correct order at the bottom of the page. There are, of course, multiple ways to solve the problem - some more efficient than others. CS Field Guide have a similar game.

*Updated: 2017-01-23*

### Linear search / sequential search algorithm

The linear search or sequential search algorithm is very straightforward, but this video explains it. It also makes an important point that students often forget: that is, while we can see all of the numbers on display at the same time in our examples, a computer cannot. Therefore no algorithm can make 'jumps' or 'assumptions' about the data - it must be searched item by item if it is unsorted. The video also includes pseudo code for the algorithm

*Updated: 2017-01-23*

### Bubble Sort algorithm

This Bubble Sort video does exactly as its name suggests - explaining the algorithm clearing with the aid of diagrams. Although it is labelled as "Java", it is relevant to all computer science students.

There is also a good explanation of the algorithm (including why it is very inefficient) plus step by step diagrams here.

*Updated: 2017-01-23*