Python Basics · Control Flow · Lesson 9 of 36
for Loops and range()
Concept
for Loops and range()
for loops in Python iterate directly over sequences. range() generates a sequence of numbers to loop over.
range(5) generates 0 through 4, not 0 through 5 — it always stops one short of its argument, which is the most common range() surprise for beginners.
- Explain the core idea behind for Loops and range().
- Predict output before running a change.
- Test one realistic and one unusual input.
- Use the result to make the next decision.
- 1. Read one concept.
- 2. Change the example.
- 3. Run, compare, and explain.
- 4. Complete the challenge below.
Self-check before continuing
Without looking at the example, describe what changes when you modify one input in for Loops and range(). Then reopen the editor and prove your explanation with a small test.
You are ready to continue when you can predict, test, and explain the result.
Your turn
Use a for loop with range() to print the numbers 1 through 10.
Ask about this lesson or your next move. The guide explains the path without taking the work away from you.
Ready for the next lesson?
Mark this lesson complete when you have finished the exercise.
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