College Board-Aligned Original Notes

AP Computer Science Principles Big Idea 1 Topic 2: Program design and development

Trace Program design and development with small examples before generalizing the pattern.

Big Idea 1: Creative Development. College Board exam weighting listed for this unit: 10%-13% of exam score.

What to Know

Track how variables, objects, lists, or data change step by step.
Watch boundary cases, indexes, loop conditions, and return values.
Use abstraction to hide details only after the behavior is clear.
Always connect this topic back to the larger unit: Creative Development.

Detailed Notes

Program design and development is easiest to learn by working through a small concrete example. Write down the input or starting situation, follow each step, and track what changes after every important operation.

In AP Computer Science Principles, AP questions often test whether you understand behavior, not whether you memorized a phrase. You should be able to explain what happens, why it happens, and what output or consequence follows.

Pay close attention to edge cases. In computing, small details such as order of steps, data representation, loop conditions, and assumptions about users can completely change the result.

Key Vocabulary

Program design and development

The planning process for a program, including purpose, inputs, outputs, algorithms, data, and testing.

Quick Practice

How would you explain Program design and development in one or two AP-style sentences?

Name the concept, apply it to a specific example or source, and explain the reasoning that connects the evidence to your answer.