Collections and repeated work

15-minute session: read for 3 minutes, trace for 3, experiment for 7, and complete the check for 2. Spend longer whenever you need.

A collection stores related values. The loop visits 1, 2, and 3, updating the total from 0 to 1, then 3, then 6. Record this trace rather than guessing. Identify the first and last valid positions in this language: Pascal can declare a 1-based array, while many other examples use zero-based containers. Add another value and update the bounds correctly. Explain what an empty collection should produce.

Indentation groups statements. def defines a function and return supplies its result. A dictionary maps keys to values. The isolated Python 3 lab has the standard library; external packages are not installed by student code.

minutes = [1, 2, 3]
total = 0
for value in minutes:
    total += value
print(total)

Expected result: 6

Practice and evidence

Keep three notes: your prediction, the actual result, and why they match or differ. The completion check grades understanding; the practice task builds skill.

Language reference