Lesson 3: while loops, and how to stop them

Module 4 · Lesson 3 · About 45 minutes · Needs: Module 4 Lessons 1 and 2 (if, elif, else, and, for loops, range())

The situation

Amira has Ben's loan, L13, in her hand. "He borrowed The War of the Worlds on day 21. How many days late is he today?" Tom adds a worry: he sometimes types nine instead of 9 into the fee program, and it stops with an error.

Both jobs repeat a step until something becomes true: count one more day until today, ask again until the answer is a number. The while loop is made for that.