Understand and explain the term abstraction. Abstraction is the process of…

The idea

Abstraction is the process of removing unnecessary detail from a problem. The key idea is selection: some details are not needed to solve the problem, so they are left out, while the details that matter are kept. A map is a common example, because it shows the roads and places needed for navigation but leaves out details such as the colour of buildings. Abstraction is not the same as simplifying by guessing or ignoring the problem; it is a deliberate decision about which detail is unnecessary for the task. A good answer identifies both the removal of detail and the purpose of that removal, which is to make the problem easier to represent or solve. In a multiple-choice question, choose the option that describes removing unnecessary detail from a problem.

What earns the marks

• States that abstraction removes detail from a problem.
• States that the detail removed is unnecessary for the problem being solved.
• Recognises that abstraction keeps the detail that is needed.
• Distinguishes abstraction from simply ignoring or avoiding the problem.
• Applies abstraction to an example such as a map that omits irrelevant features.

Common mistakes and how to put them right

• Describing abstraction as adding more detail to a problem.

  Put it right: Abstraction removes unnecessary detail.

• Confusing abstraction with removing all detail.

  Put it right: Only unnecessary detail is removed while relevant detail is kept.

• Treating abstraction as the same as decomposition.

  Put it right: Abstraction selects which detail to omit, whereas decomposition breaks a problem into smaller parts.

Exam tips

• Look for the option that mentions removing detail and links it to a problem.
• Check whether the option says the detail is unnecessary, not simply missing.
• Use a concrete example such as a map to test whether the option describes abstraction.