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Knowledge/A Level/H446/02 Algorithms and programming/Thinking abstractly/The differences between an abstraction…

The differences between an abstraction and reality

The differences between an abstraction and reality.

2.1.1 Thinking abstractly

Thinking abstractly — Note 3 of 4

Candidates need to understand how reality differs from an abstraction. Candidates may be given a scenario or example and be asked how the abstraction differs from the reality.

What you need to know

An abstraction is a simplified model, not the real thing. Because detail has been removed, an abstraction may not behave exactly like reality, and you need to identify where and why they differ.

What to know

  • An abstraction keeps only the features relevant to the problem; reality contains all the detail.
  • Abstractions can make assumptions that are not always true, e.g. that traffic always flows at the speed limit.
  • Results from an abstraction are approximations; the more detail removed, the less accurate the model may be.
  • Variables, objects and data structures in a program are abstractions of real-world things, e.g. a 'Customer' object only stores the details the system needs.
  • Choosing the right level of abstraction is a trade-off between accuracy and simplicity or speed.

Exam technique

  • Tip:When asked how an abstraction differs from reality, name specific details that have been left out and explain the effect of leaving them out.
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Thinking abstractly

Note 3 of 4

  1. 1The nature of abstraction
  2. 2The need for abstraction
  3. 3The differences between an abstraction and reality
  4. 4Devise an abstract model for a variety of situations
Topic overview