Data Types
Time 1.3 hrs

Difficulty Beginner
Prerequisites Variables
Departments Science
Authors Sandra Kuipers
Groupings Individual
Minimum Year Group None


Data comes in many forms: numbers, letters, symbols, and more. This unit looks at primitive data types and how they make up the building blocks of all programming languages.


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10 mins
What is Data?
Getting Started
  • A computer stores information as data.
  • A bindary digit (bit) is the smallest form of data.
  • Binary can be used to store 1s and 0s.
  • All other types of data start with binary, and are converted into something more meaningful:

5 mins
Types of Data
  • The variables in our code can store many different types of data.
  • Chances are, you've already seen and used some data types in your code.
  • Some programming languages are loosely typed:
    • This means they don't require you to declare a type upfront.
    • For example, a var in JavaScript can hold any type of data.
    • We can also combine different types without creating an error.
    • In JavaScript, the code "Hello Cat" + 5; will create the string "Hello Cat5".
  • Some programming languages are strictly typed:
    • This means each variable must be declared with its data type.
    • For example, in C#, a string myVar; can only hold data that is a string.
    • Combining variables with different types generally creates an error.
  • The following are some of the most common types of data.
5 mins
True and False
  • The boolean type has only two values: true and false.

    This type is commonly used to store yes/no values: true means “yes, correct”, and false means “no, incorrect”.

    For instance:

    var thisThing = true;
    var thatThing = false;
  • We’ll cover booleans more deeply in the unit on Logical operators.

    It helps to remember booleans as a switch: they can only be on or off (true or false)
5 mins
  • An integer is a type of number that does not have a decimal point.

  • A whole number, including negative numbers.

    var x = 10;
    var y = -36;
  • There are many operations we can do with numbers, such as multiplication *, division /, addition +, subtraction -, and so on.
    var score = 42 + 500;
5 mins
Numbers with Decimals
  • A float (or floating point number) is a type of number that has a decimal point.
    var distance = 4.5;
    var hours = 1.125;
  • To remember Floats vs Integers, I think of them floating on their decimal point like a life-preserver.
5 mins
Letters and Symbols
  • A string is any number of words, letters and symbols surrounded by quotes:
    var question = "What day is it?";
    var answer = "Monday";
  • Strings can use either 'single quotes' or "double quotes"
    var answer1 = "Abolsutely";    
    var answer2 = 'Not sure';     
    var answer3 = "It's alright";  

    It helps to think of them as a bunch of letters, connected on a string:
5 mins
  • Often we need to store a list of things.
  • An array is a special variable, which can hold more than one value at a time.
    var cars = ["Volvo", "BMW", "Tesla"];
    var fibonacci = [0, 1, 1, 2, 3, 5, 8, 13];
  • Spaces and line breaks are not important. A declaration can span multiple lines:
    var fruit = [
  • We’ll cover these more in the unit on Arrays.
More Data
Lots more
  • There's many more types of data.
  • The data types here are often called primitive types.
  • This is because they're the basic building-blocks of more complex data.
  • Other types of data, like objects, are made up of primitive types.
40 mins
Digital Scavenger Hunt
  • Take a moment to consider how the above data types might exist in the world around you.
  • Your goal is to search for images to help visualize these different data types.
    • You may search the web for images.
    • You are also welcome to grab your phone and search the school.
  • The pictures in this unit are examples, please don't copy them :)

  • Open up Google slides and create some slides for this unit.
  • Add one slide called Data:
    • Include a short definition, in your own words.
    • At least one link to a website or video that helps explain this concept.
  • Then, add one slide for each of the following data types:
    • Boolean
    • Integer
    • Float
    • String
    • Array
  • For each slide, add:
    • A short definition, in your own words.
    • An image to help illustrate this concept.
  • Once you have finished, submit the link to your slideshow as evidence of learning in this unit.



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