Computer Science Principles Unit 5 Chapter 2 Lesson 11: While Loops

This lesson demonstrates how a slight manipulation of a conditional statement can allow for the creation of a new and powerful tool in constructing programs, a while loop. Students are introduced to a while loop by analyzing the flow chart of a conditional statement in which the "true" branch leads back to the original condition. Students design their own flowcharts to represent a real-world situation that could be represented as a while loop, and they learn how to recognize common looping structures, most notably infinite loops. Students then move to App Lab, creating a while loop that runs exactly some predetermined number of times. While learning about creating while loops, students will be introduced to many of the common mistakes early programmers make with while loops and will be asked to debug small programs. They finally progress to putting if statements inside a while loop to count the number of times an event occurs while repeating the same action. This activity will recall the need for counter variables and foreshadows their further use in the following lesson.

Students will be able to:
- explain that a while loop continues to run while a boolean condition remains true.
- translate a real-life activity with repeated components into a form that could be represented by a while loop.
- analyze a while loop to determine if the initial condition will be met, how many times the loop will run, and if the loop will ever terminate.
- write programs that use while loops in a variety of contexts.

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