Trace the lists: indexes, loops and append: coding worksheet for Grades 9–11, page 1 preview

Coding worksheet · Coding

Trace the lists: indexes, loops and append · Grades 9–11

Read 6 short Python programs about list indexes, len, append and loops over lists and work out by hand what each one prints or the final value of a variable. Builds careful code tracing.

Grades 9–11 · ages 14 to 17
Easy
25 to 35 minutes
1 page
Free

The answer key is a separate page for grown-ups. Sign in to download it.

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The programs to trace

Directions: Trace each program line by line without a computer. Keep a note of every variable as it changes, then write exactly what the program prints or the final value.

1 What is printed?
1 nums = [14, 10, 20, 3, 19]
2 print(nums[1] + nums[-2])
2 What is printed?
1 nums = [14, 34, 33, 36, 12]
2 best = nums[0]
3 for n in nums:
4 if n > best:
5 best = n
6 print(best)
3 What is printed?
1 nums = [8, 3, 7]
2 for i in range(len(nums)):
4 print(nums)
4 What is printed?
1 nums = [11, 6, 14, 2, 16, 4]
2 total = 0
4 if n > 9:
5 total += n
6 print(total)
5 What is printed?
1 values = []
2 for i in range(5):
4 print(len(values), values[-1])
6 What is printed?
1 nums = [19, 17, 17, 13]
2 print(nums[2] + nums[-2])

What your child practices

Your child builds careful code tracing. The skill is “Variables”: use named values such as a score, lives or a timer that a program changes and checks.

Grades and ages: Grades 9–11, ages 14 to 17
Time: About 25 to 35 minutes
Subject: Coding
Level: Easy for Grades 9–11
Answer key: Yes, for grown-ups who sign in
Printing: 1 page, US Letter or A4, low-ink option
Updated: October 15, 2026

How to use it

Work through the first program together, one line or arrow at a time. Then let your child work through the rest, showing their thinking on the page. It is one of the easier sheets for Grades 9–11, good as a warm-up or a first look at the skill.

An answer key comes with it as a separate page that grown-ups download after signing in.

Tip for grown-ups: Have your child write each variable's value beside its line as they trace.

Done on paper? A grown-up can record it on the child's page in PlayOwl; downloading alone doesn't count as finished.