Python lesson 17: Changing lists
US version. US grades and US spelling. · UK version of this lesson
append(x) adds x to the end; insert(i, x) puts x at index i; remove(x) takes out the first x. A complete 40-minute Python lesson for complete beginners (Grades 6–7), from Unit 5: Lists. It runs right here in your browser – nothing to install.
- Time
- 40 minutes + 20 min homework
- Grade
- Grades 6–7 (ages 11–12)
- You need
- A computer or tablet, paper and a pencil
- Graded
- Instantly, with explanations
For parents: how to use this lesson
You don't need to know Python yourself. The lesson explains each step on screen, the way Mr Babbage, our Head of Computing, likes it: a worked example first, then a go for your child. Code questions run your child's program in the browser and grade it straight away.
- Read what your child will learn together.
- Press Start the lesson below. Sit with your child for the teaching and the worked example (about 16 minutes): ask them to say what each line does.
- Let them do the practice on their own. When code goes wrong, the error message is a clue – let them read it out and try again before you help.
- Finish with the exit questions and the talk question: “Which list method would a to-do app use most?”
- Later that day or the next day: the homework (20 minutes), then a practice test.
Watch out for
- print(nums.sort()) shows the sorted list. Run it: it shows None.
- append() adds to the front. Print the list after appending.
Miss Lovelace's tip for home: ask your child to explain one line of their program to you in their own words. If they can explain it, they understand it – and every error message is a clue, not a failure.
What your child will learn
Learning goal: add items with append() and insert().
Success looks like
- I can add items with append() and insert().
- I can remove items and sort a list.
- I can check membership with in.
Key words
append · insert · remove · sort · in
What to have ready
- A device with a web browser (the code runs in the browser – nothing to install)
- Paper for tracing
- A keyboard helps for typing code (a tablet or phone works too)
The big ideas (for the adult)
append(x) adds x to the end; insert(i, x) puts x at index i; remove(x) takes out the first x.
sort() puts the list in order and gives back None – so print the list on the next line.
"cat" in pets is True if "cat" is in the list. Check before you remove.
Worked example
a = ["judo", "rowing", "golf"]
print("rowing" in a)It prints:
True
The lesson, step by step
| Part | Time | How it is checked |
|---|---|---|
| Starter | 5 min | Graded by Classfern |
| Teaching input | 8 min | Read, watch and talk |
| See it, then predict | 8 min | Graded by Classfern |
| Put it in order, write it, fix it | 14 min | Graded by Classfern |
| Closure and exit ticket | 5 min | Graded by Classfern + self-check |
The lesson
It runs here on the page. No sign-up and no names – progress is kept only in this browser. Each visit picks a new mix of questions.
Homework
20 minutes: 7 questions – predict what code prints, write or fix a short program, and check the key ideas – then a short reflection. New questions every time, all graded instantly.
Practice tests
Curriculum
CSTA K–12 Computer Science Standards (2017), grades 6–8: 2-AP-11 – Create clearly named variables of different data types and operate on them.
The standard codes are CSTA's; the descriptions are our own words.
Our lessons and questions are our own. They are not written or endorsed by any government department, testing agency or exam board. Python is a registered trademark of the Python Software Foundation; Classfern is not affiliated with or endorsed by it.