Modules and Imports Checkpoint

Optional

20 min · Beginner

A review of this module. Skip it if you feel confident; the next module does not need it.

Fix the mistakes

The slips that cost marks in this module. Spot each one, then check the fix.

Test what you know about imports, your own modules, the main guard and pip. Each problem uses only the standard library, so every program runs as one file.

Pick the right import form

Use import x when you want each name's source to stay clear, from x import y for a few names you use often, and as for long module names.

Python

1import math2from statistics import mean3import datetime as dt4
5print(math.floor(4.7))6print(mean([70, 80, 90]))7print(dt.date(2026, 11, 3).weekday())

Example 1 · Statistics for a list of marks

Python

1import statistics2
3marks = [72, 85, 90, 67, 80]4print(statistics.mean(marks))5print(statistics.median(marks))6print(max(marks) - min(marks))

Output

78.8
80
23

What this code does

statistics is a standard library module, so no pip install is needed.
mean is the average, and median is the middle value of the sorted list.

Example 2 · Overdue invoices

Python

1from datetime import date2
3today = date(2026, 11, 3)4due_dates = ["2026-10-28", "2026-11-20"]5for text in due_dates:6    due = date.fromisoformat(text)7    print(text, (today - due).days)

Output

2026-10-28 6
2026-11-20 -17

What this code does

fromisoformat reads text in year-month-day form.
A positive number means the invoice is that many days late. A negative one means it is not yet due.

weekday() counts Monday as 0, so 3 November 2026 (a Tuesday) gives 1. Each form creates different names: math, mean and dt.

A module with a main guard

Keep logic in functions and run it from a main() that sits under the guard. Another file can then import the functions safely.

Python

1def pass_rate(marks, limit=40):2    passed = [m for m in marks if m >= limit]3    return len(passed) / len(marks) * 1004
5
6def main():7    print(pass_rate([72, 35, 90, 41]))8
9
10if __name__ == "__main__":11    main()

Example 3 · A module-style script

Python

1def to_celsius(f):2    return round((f - 32) * 5 / 9, 1)3
4
5def main():6    for temp in [32, 98.6, 212]:7        print(temp, to_celsius(temp))8
9
10if __name__ == "__main__":11    main()

Output

32 0.0
98.6 37.0
212 100.0

What this code does

Logic lives in to_celsius, which another file could import.
main() runs only when this file is started directly.

Imported from another file, this module prints nothing. Run directly, it prints 75.0.

Reading an import error

ModuleNotFoundError means nothing on the import path matches. Check the spelling, the folder, and whether the package needs python -m pip install.

Python

try:    import pandas_not_hereexcept ImportError as err:    print(f"Cannot import: {err.name}")

Catching ImportError is useful for optional tools. Never hide a missing required package without telling the user.

Finish up

Mark complete & continue

Next: Reading and Writing Text Files

1def pass_rate(marks, limit=40):2 passed = [m for m in marks if m >= limit]3 return len(passed) / len(marks) * 1004 5 6def main():7 print(pass_rate([72, 35, 90, 41]))8 9 10if __name__ == "__main__":11 main()