2.1.1 Thinking Abstractly Exam Questions

Past paper questions

1. Question 1H446/022 marks

   Define the term 'abstraction' in the context of computational thinking.

   Your answer (optional, saved in this browser)
   Show mark scheme

   Removing unnecessary detail / Focusing on important aspects / Hiding complexity / Simplifying a problem to its essential features (2 marks)

   Mark yourself: how many marks did you get?

   012/ 2
2. Question 2H446/024 marks

   Explain how abstraction is used when designing a class diagram for an online shopping system.

   Your answer (optional, saved in this browser)
   Show mark scheme

   Focus on relevant attributes (name, price) not physical properties / Group similar items into classes / Hide implementation details / Use inheritance to share common properties / Show relationships not internal workings (4 marks)

   Mark yourself: how many marks did you get?

   01234/ 4
3. Question 3H446/024 marks

   Describe two benefits of using abstraction when developing software.

   Your answer (optional, saved in this browser)
   Show mark scheme

   Reduces complexity - easier to understand / Allows focus on relevant details / Enables code reuse / Makes maintenance easier / Allows working at higher level / Hides implementation from users (4 marks - 2 per benefit)

   Mark yourself: how many marks did you get?

   01234/ 4
4. Question 4H446/023 marks

   A map application shows roads and landmarks. Explain how abstraction has been used in the design of this application.

   Your answer (optional, saved in this browser)
   Show mark scheme

   Roads simplified to lines / Buildings shown as simple shapes / Ignores physical texture/material / Only shows relevant features for navigation / Scale adjusted to remove unnecessary detail / Color coding for different road types (3 marks)

   Mark yourself: how many marks did you get?

   0123/ 3
5. Question 5H446/024 marks

   Explain the difference between representational abstraction and abstraction by generalisation.

   Your answer (optional, saved in this browser)
   Show mark scheme

   Representational abstraction: Removing unnecessary details while keeping essential information / Simplifying representation of real-world objects Abstraction by generalisation: Grouping similar entities by common characteristics / Creating categories or classes / Identifying shared properties (4 marks - 2 per type)

   Mark yourself: how many marks did you get?

   01234/ 4
6. Question 6Practice question · H446/02 style4 marks

   A school wants a program that produces its lesson timetable. Devise an abstract model for this problem by identifying two features that must be included and two real-world details that can be ignored. Justify your choices.

   Your answer (optional, saved in this browser)
   Show mark scheme

   Include (1 mark each, max 2), e.g.: • Rooms and their capacities • Teachers and when they are available • Classes / subjects and the number of periods each needs Ignore (1 mark each, max 2), e.g.: • The colour or decoration of rooms • The names of individual students (only class sizes matter) • The weather / what teachers wear Justification: included features affect whether a timetable is valid; ignored details do not change the solution (4 marks)

   Mark yourself: how many marks did you get?

   01234/ 4
7. Question 7Practice question · H446/02 style3 marks

   Explain, using an example of each, the difference between representational abstraction and abstraction by generalisation.

   Your answer (optional, saved in this browser)
   Show mark scheme

   • Representational abstraction removes unnecessary detail so only what is needed remains • e.g. a tube map shows stations and connections but not real distances or geography • Abstraction by generalisation groups things into categories / a hierarchy according to shared characteristics • e.g. treating cars, buses and lorries as 'vehicles' in a parking system (3 marks – 1 per point, max 3)

   Mark yourself: how many marks did you get?

   0123/ 3
8. Question 8Practice question · H446/02 style4 marks

   Describe two ways in which abstraction is used when writing a program in a high-level language.

   Your answer (optional, saved in this browser)
   Show mark scheme

   Any two, 2 marks each: • Variables abstract memory addresses – the programmer uses a name rather than a binary address • Functions / procedures hide their internal code so they can be called by name (procedural abstraction) • Data structures such as lists and objects hide how the data is actually stored in memory • A single high-level statement stands for many machine-code instructions (4 marks)

   Mark yourself: how many marks did you get?

   01234/ 4