Collection selection
Choosing a collection: a list for an ordered sequence, a tuple for values that must not change, a dictionary when each value has a natural label like "name" or "score".
Python for Kids · Class 7 · Module 5 of 9
Lists, Tuples and Dictionaries
Different jobs need different containers. Choosing well is half the solution.
8 sessionsSessions 33–40
4 weeksTypical pace
Foundation to IntermediateLevel
Class 7Python & Coding
The big idea
Lists keep order, tuples refuse to change, and dictionaries look things up by name instead of position. Once students can nest them, they can model almost any real-world information.
Why it matters
Choosing the right structure often removes the need for clever code entirely. It is the earliest form of genuine design judgement.
Unpacked
What you will actually learn
Three core ideas, each taught with worked examples and then practised until it feels obvious.
Nested data
Nested data means collections inside collections — a list of dictionaries is how almost every real dataset on the internet is shaped.
Updates
Updating safely means knowing which structures can change in place and which cannot, and what happens when two names point at the same list.
Did you know?
Dictionary lookup barely slows down as it grows. Searching a million-key dictionary takes roughly the same time as searching one with ten.
Common mix-up
“A dictionary is just a fancy list.” A list finds by position; a dictionary finds by meaning. That difference changes how you design the whole program.
Session by session
Your 8-session journey
Sessions 33–40 of the 72-session year, at two one-hour sessions per week.
- 1
Warm-up and big picture
Where this module fits, what you will build, and a hands-on starter that gets everyone curious about collection selection.
- 2
Collection selection
Guided teaching on collection selection, worked through together with the teacher.
- 3
Collection selection — practice lab
Independent practice, small challenges and one deliberate mistake to diagnose.
- 4
Nested data
Guided teaching on nested data, building directly on the previous two sessions.
- 5
Nested data — practice lab
Applied tasks that combine collection selection and nested data in one piece of work.
- 6
Updates
Updates introduced and practised, completing the toolkit needed for the project.
- 7
Project build
Guided build session for the module project: Student score tracker.
- 8
Test, present and reflect
Finish, test against the checklist, present the work and explain the decisions behind it.
Project lab
Student score tracker
Every module ends with something the student built themselves and can demonstrate. This is the piece that goes into their portfolio and gets explained out loud at the end of session 40.
Try this at home
Store five classmates as a list of dictionaries with name, subject and score, then print the top scorer without sorting by hand.
It is finished when
- It works from start to finish without breaking
- You can explain every part of it in your own words
- You tested it and improved at least one thing afterwards
- Someone else used or understood it without your help
By the end of this module
Students finishing Module 5 can:
- Explain and use collection selection without prompting
- Explain and use nested data without prompting
- Explain and use updates without prompting
- Build and finish student score tracker
- Test your own work and correct what you find
- Talk an adult through what you made and why
Word bank
The vocabulary introduced here, in plain language:
- tuple
- An ordered collection that cannot be changed.
- dictionary
- A collection of key–value pairs.
- key
- The label used to look a value up.
Module challenge
Think you have got this?
0 XPLevel 1 · Curious Beginner
6 quick questions drawn from this module — vocabulary, the project you build, and a myth-or-fact round. Every wrong answer explains itself, so a mistake still teaches you something.
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