Variables and constants in programs
Lesson details
Learning outcome
I can apply appropriate naming conventions and explain the differences between variables and constants.
Key learning points
- Naming conventions improve code readability and maintainability.
- A variable is a named piece of data stored in a computer’s memory.
- A variable can be accessed and changed by a computer program.
- Variables must be declared and assigned values in a program.
- Constants hold fixed values that do not change throughout the running of the program.
Keywords
Variable - a named piece of data stored in a computer’s memory which can be accessed and changed by a computer program
Declaration - the process of stating the name of a variable or constant and defining its data type
Initialisation - assigning a starting value to a variable to let the compiler know that a memory location is required
Constant - a value that cannot be changed during the execution of a program
Common misconception
You can define a constant in any programming language.
Python does not have constants. But if you want a value to be treated as a constant, it's a common naming convention for the identifier to be written in capital letters.
Teacher tip
Demonstrate the use of constants in a programming language that supports them. Pupils should see how constants cannot be changed once initially assigned.
Equipment
Pupils will need access to a device that can edit and run Python programs. Examples in this lesson use the RPF Code Editor https://oak.link/python-editor
Licence
Lesson video
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Prior knowledge starter quiz
6 Questions
Q1.What does IDE stand for?
Q2.Match the terms to their definitions:
data sent to a program to be processed
information produced by a computer system
an application that facilitates the writing and running of programs
Q3.What feature uses colours to distinguish code elements?
Q4.What Python function is used to receive data from the user during program execution?
Q5.What Python function is used to display output to the user during program execution?
Q6.What is the primary purpose of output devices?
Assessment exit quiz
6 Questions
Q1.What is a variable?
Q2.What is a constant?
Q3.What is the purpose of naming conventions?
Q4.What is initialisation in programming?
Q5.Is it possible to define a constant in Python?
Q6.What variable name would be commonly used to store a first name in Python?
To help you plan your 10 computer science lesson on: Variables and constants in programs, download all teaching resources for free and adapt to suit your pupils' needs...
To help you plan your 10 computer science lesson on: Variables and constants in programs, download all teaching resources for free and adapt to suit your pupils' needs.
The starter quiz will activate and check your pupils' prior knowledge, with versions available both with and without answers in PDF format.
We use learning cycles to break down learning into key concepts or ideas linked to the learning outcome. Each learning cycle features explanations with checks for understanding and practice tasks with feedback. All of this is found in our slide decks, ready for you to download and edit. The practice tasks are also available as printable worksheets and some lessons have additional materials with extra material you might need for teaching the lesson.
The assessment exit quiz will test your pupils' understanding of the key learning points.
Our video is a tool for planning, showing how other teachers might teach the lesson, offering helpful tips, modelled explanations and inspiration for your own delivery in the classroom. Plus, you can set it as homework or revision for pupils and keep their learning on track by sharing an online pupil version of this lesson.
Explore more key stage 4 computer science lessons from the Programming: sequence unit, dive into the full secondary computer science curriculum, or learn more about lesson planning.