How it works
Programs improve through cycles of prototype, test, feedback, and revision.
Use small tests or mockups to decide what to improve before building every feature.
Common error
Waiting until the program is complete to test usually hides problems until they are harder to fix.
Worked example
User testing finds that an unlabeled icon prevents students from saving a task.
Data / pseudocode
Prototype 1: 2 of 6 users save successfully
Revision: add visible Save label
Prototype 2: 5 of 6 users save successfullyThe revision responds to observed behavior and the follow-up test measures the same task. The result supports improved usability in this small test; it does not prove all users will succeed. Continue testing with varied users and investigate the remaining failure.
Exercises
1.2.1
Why is a small prototype useful before implementing every feature?
Show solution
It lets users and developers test important assumptions early, so major interface or requirement problems can be corrected before they become expensive to change.
1.2.2
Write a second revision cycle for users who still cannot locate saved tasks.
Show solution
Observe where users look, prototype a clearer task-list entry or confirmation, test the same retrieval task with representative users, and revise based on the results.