TOpic 2 lists (array)
English National Curriculum:
Key Stage 1
Tooltip content
TO USE TECHNOLOGY PURPOSEFULLY TO CREATE, ORGANISE, STORE, MANIPULATE AND RETRIEVE DIGITAL CONTENT.
learning objectives
Tooltip content
to understand how to create, assign, change and swap memory boxes (variables) in a list (array).
success criteria
- I can describe the two things that are essential to access the values in the list. These are a name and an index.
- I can perform a value swap between two items (memory Boxes) in a list.
top tips
- List are used to store sequences of information to be referenced to in a computer program.
- Lists also provide a way of labelling data with a descriptive name and an index, so our programs can be understand more clearly by the reader and by ourselves.
- We assign, update and swap values in a list.
- In computer science, lists can be understood as arrays of data.
Common misconceptions
- You have no access to elements in a list.
- In computing, every list has to have a name and indices. Each index indicates a position in the list, such as 1, 2 or 3. In some computing languages, the index start from 0.
- You don't need anything to swap the values in a list.
- A temporary value holder, a Memory Box, is required in order to swap values.
Arrays
Lists are used to hold a series of Memory Boxes. In computing, they are called Arrays.
For example, the array below shows information about the exam scores of 6 students. The indices or locations of elements in the list, help us locate each student, and the value at a particular index shows their exam score.
TOPIC BACKGROUND READING
Lists are a collection of memory locations, there are often referred to as a row of ‘buckets’ or ‘bins’. These buckets can hold many forms of data, from a single piece of information to a collection of information, and this information is usually of the same type or the same subject. For our examples, each bucket or location holds an individual memory box.
Lists are formed with three pieces of information:
- Name, a name is given to the list. Similar to a memory box, this name is used to identify the list when it is needed. The name should usually also help to identify the contents of the list. For example a list of animals could be called AnimalList or animal_list.
- Elements are the objects within the list. These can be of various in a list for a particular reason. For instance in a school, students could be grouped by class into class lists.
- Index refers to a number we use to reference a location of an element in the list. Every element in a list is given a number, and when needed can be used to cal that element into action. The index is iterative so each element after the last is given the next appropriate value i.e 1, 2, 3, 4, 5. Different programming languages can use different starting points for the first element, but the most common way is to start at index zero (0), so 0, 1, 2, 3, 4, etc. One (1) is chosen as a starting point through the text to make it easier for students, so 1, 2, 3, 4, etc.
