Programming & Paradigms is a core part of A-Level Computer Science. Revise the key concepts and common mistakes below, then lock them in with the free games.
Key concepts
VariableA named store whose value can change.
Data typesInteger, real, Boolean, character and string.
SelectionChoosing actions with IF/ELSE statements.
IterationRepeating code with FOR and WHILE loops.
Functions & proceduresReusable named blocks of code (subroutines).
OperatorsArithmetic, comparison and logical operators.
ClassA blueprint defining fields and methods for objects.
ObjectAn instance of a class with its own field values.
EncapsulationHiding internal state behind a public interface.
FieldA data member of an object — its state.
MethodA function defined inside a class.
ConstructorA special method called when an object is created.
InheritanceA class deriving fields and methods from a parent class.
PolymorphismOne interface, many forms — same call, different behaviour by type.
Common mistakes to avoid
Questions where students often pick the tempting wrong answer — make sure you know the right one:
What is the scope of a local variable?✗ Accessible everywhere in the program. ✓ Accessible only within the function/block where it is declared.
What is polymorphism in OOP?✗ Having multiple classes with the same name. ✓ The ability of different classes to respond to the same method call in their own way.
What is encapsulation in OOP?✗ Putting code inside other code (nesting). ✓ Bundling data and methods together while restricting direct access to internal state.
What does inheritance allow a subclass to do?✗ Replace the superclass entirely. ✓ Reuse and extend the attributes and methods of its superclass.
An object is best described as:✗ A class blueprint ✓ An instance of a class
Practise Programming & Paradigms — free games
Test yourself with these quick revision games for this topic:
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