Lesson 3.1 · College Board Unit 2
For Loops
A for loop initializes once, checks its condition before each iteration, and updates after the body. Track the first included and first excluded value.
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Unit 3: Loops and Iteration
Repetition, and the accounting that makes it correct. The unit is less about loop syntax than about knowing what each variable means after one pass, which is the only reliable way to get bounds and accumulators right.
Lessons and exercises
Lesson 3.2 · College Board Unit 2
While Loops
A while loop can run zero times. Identify a changing quantity that eventually makes the condition false.
Lesson 3.3 · College Board Unit 2
Nested Loops
For each outer iteration, the inner loop starts again. When inner bounds depend on the outer index, count each row separately.
Lesson 3.4 · College Board Unit 2
Accumulators and Counters
A counter records how many items satisfy a condition; an accumulator combines their values. Initialize both outside the traversal.
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