Lesson 8: Continuous and Discrete Revision Notes
Lesson Objectives
By the end of this lesson, you should be able to:
Grade C: Identify a variable as either continuous or discrete. A variable (something that can change in an experiment) can be one of two types.
Grade B: Know which graph to draw for continuous and discrete data. Continuous data include measurements that can fall within a range, including fractions. Discrete data consist of specific, separate values and cannot be fractions.
Grade A: Draw a line graph with help. Line graphs are used for continuous data to show trends over time or changes.
Understanding Continuous and Discrete Variables
Variables in experiments help us understand how changes affect outcomes. Knowing whether a variable is continuous or discrete is crucial for correct data analysis and presentation.
Continuous Variables: Imagine you're measuring how much juice you pour into a glass. You might fill it to exactly 1.2 liters, 1.25 liters, or even precisely 1.254 liters. This kind of variable is continuous because the amount of juice can be any value within a range, including very precise numbers with decimals (fractions).
Discrete Variables: Now, think about counting something that can't be split into smaller parts, like how many books are on your shelf. You might have 20 books, 21 books, or 22 books, but you won't have 20.5 books because books are counted in whole numbers. This type of variable is discrete because it involves counting individual, separate items.
Choosing the Right Graph
For Continuous Data: Use a line graph. It's perfect for showing how something measured can change in a smooth, continuous way. For instance, tracking temperature changes throughout a day.
For Discrete Data: Opt for a bar chart. It's ideal for comparing different groups or counting items, like tallying how many students got each possible score on a quiz. (see my lesson on Bar charts here.)
Examples of Continuous and Discrete Variables
Height: Continuous, as it includes very precise measurements that can even use fractions of a centimetre.
Number of Pets: Discrete, because pets are counted in whole numbers and you can't have a fraction of a pet.
Test yourself
Keywords and Definitions
Continuous Variable: A type of variable that can have any value within a given range, including numbers with fractions (parts of whole numbers).
Discrete Variable: A type of variable that can only take specific, separate values, usually counted in whole numbers.
Variable: An element or factor in an experiment that can change and influence the results.
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