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Paper 1 OOP Drills

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Paper 1 OOP Drills

These are original Paper 1-style practice questions. They use concrete OOP scenarios so the answers can be checked exactly.

Detailed answers are in Paper 1 OOP Answers.

Revise the topic hub first:

Questions

Question 1: Class vs Object

In a library program, Book is defined with attributes title and copies. The program creates:

book1 = Book("Algorithms", 3)

Identify the class and the object, and explain the difference. [2]

Question 2: Attributes and Methods

A Student class stores student_id, name, and mark. It can update the mark and report whether the student has passed.

State three suitable attributes and suggest two suitable method names for this class. [5]

Question 3: Encapsulation

A BankAccount object stores a private-style attribute _balance. Directly setting _balance = -500 would make the account invalid.

Explain why the balance should be changed through a method such as withdraw(amount) instead of direct access. [3]

Question 4: Inheritance

A school system has classes Person, Student, and Teacher.

Student and Teacher both have name and email. Student also has class_name. Teacher also has department.

Describe the inheritance relationship and state which attributes belong in the superclass. [4]

Question 5: Polymorphism

EmailNotification and SMSNotification are subclasses of Notification. Both implement a method named send().

For:

EmailNotification.send() -> "email sent"
SMSNotification.send() -> "sms sent"

Explain how this is polymorphism. [3]

Question 6: Implementation Independence

A BankAccount class currently stores one internal _balance value. Other code uses only these public methods:

deposit(amount)
withdraw(amount)
get_balance()

Later, the class may change its internal implementation to store a list of transaction amounts instead of one _balance value. The public method names and behaviour remain the same.

Explain why code using BankAccount may not need to change, and name the OOP idea involved. [5]

Question 7: Generalisation

Two classes have these attributes:

PrintedBook: title, author, pages, shelf
EBook: title, author, pages, file_size

Suggest a superclass and state which attributes should be moved into it. [3]

Question 8: Scenario Update

An existing design has superclass Vehicle and subclasses Car and Bus. All vehicles have registration and speed. Car has num_doors; Bus has capacity.

A new Taxi type is needed with registration, speed, and licence_number.

Explain how to update the design. [3]

Question 9: Benefits

Using the Vehicle, Car, Bus, and Taxi design, give two benefits of using inheritance in this scenario. [2]

Question 10: Class Attribute vs Instance Attribute

A Student class stores each student’s name. It also needs to keep a shared count of how many Student objects have been created.

For the following objects:

s1 = Student("Aisha")
s2 = Student("Bo")

State whether name and count should be instance attributes or class attributes, and explain why. [4]

Review Checklist

After attempting these questions, check whether you can:

  • distinguish class, object, attribute, and method in a concrete scenario;
  • explain encapsulation as controlled state change;
  • identify superclass/subclass relationships;
  • explain polymorphism as the same method call with subclass-specific behaviour;
  • explain implementation independence;
  • distinguish instance attributes from class attributes.

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