Python Puzzler #2948

Python Puzzlers card for the topic loops

Challenge type: Python Puzzlers  ·  Difficulty: ★★★☆☆ Medium  ·  Topic: loops

Read this Python program carefully. Don’t run it yet! Can you work out exactly what it prints?

print(list(range(3, 8, 5)))

Choose an answer

ChoiceOutput
A
[3]
B
[3, 4, 5, 6, 7]
C
[3, 8]
D
[4]
Need a hint?

Pretend you are the computer. Go through the program one line at a time, and write down every variable’s value on paper as it changes. Programmers call this a trace.

Grown-ups: Reading code and predicting what it does is a key programming skill. Once your child has chosen an answer, run the code in IDLE together to check.

For teachers and grown-ups

Skills practised: Code reading, tracing variables, and understanding Python syntax.

The big idea: Predicting a program's output before running it builds a solid mental model of how code works.

Questions to ask:

  • What is the value of each variable after every line?
  • Which line decides the output?
  • What small change would make it print something different?

Take it further: Children use a trace table on paper for the code, then run it in IDLE to check, and change one value to make a new puzzle for a friend.