We return to the topic of iteration! A ``` while ``` loop allows us to deal with indefinite iteration--iterating an unknown (or not easily knowable) number of times until some stopping condition is reached.

### Lecture Prep

Read: 2 short sections from Ch 7 of textbook
1. 7.3 The ``` while ``` statement
2. 7.4 ``` break ```
Do not use ``` break ``` in any work you submit in CS1110. We want you to know about this keyword, but you should not use it (for now). Instead, practice using the ``` while ``` loop in situations where the ``` while ``` loop is well suited.
And Watch:
1. While-Loop Traces (9 minutes) Compare the ``` for ``` loop and the ``` while ``` loop for calculating the sums of squares ( total.py , flow.py )
2. While-Loop Ranges (6 minutes) Warm up by replacing a for-loop that iterates over a ``` range ``` with a ``` while ``` loop ( pattern1.py )
3. While-Loop Patterns (6 minutes) Two typical patterns for setting up ``` while ``` loops: use a goal condition; use a boolean tracking variable ( pattern2.py , pattern3.py )

### Lecture materials

Slides: individual slides for viewing , 6-up layout for printing