Grids: Lists Inside Lists
Python Programming 2 Grades 9–12 4-day lesson 29 deliverables Teach students to store rows and columns in Python as a list of lists. Students mark cells on a paper grid, use grid[row][col] and trace nested loops. They print and count a grid of recital seats and check typed row and seat numbers. Then they build a pixel grid of color names, draw it with turtle cells and find the first full row.
● Instant download · Lifetime access · Editable & print-ready
Print + digitalPDF, PowerPoint, Word & Google
Answer keysA key for every page
Built-in assessmentExit tickets + lesson quiz
45-minute daysEvery day planned and timed
Short coding levels practice this lesson in CodeGrove, our code lab that runs in the browser. Students write the program, run it and check it, with no account and nothing to install. Use them with the lesson or as practice later.
See the levelsWhat does this lesson cover?
Students often mix up the row and the column, or get lost when one loop sits inside another. This lesson puts the row first every time. Students trace the outer loop and the inner loop on paper before they print, count and draw.
The labs on Days 2 and 3 and the quiz task on Day 4 run online in CodeGrove, our in-browser code lab, so students need a computer or tablet on those days. The Seat Map and Pixel Grid levels practice printing, counting, building and drawing grids with nested loops, and checking typed row and seat numbers. CodeGrove is free, with no accounts, sign-ins or installs.
Seat Map
Students print and count a grid of recital seats with nested loops and book a seat from checked typed numbers in CodeGrove.
Everything that's included
00 Start Here
- READ FIRST: every file in the lesson and when you use it
- Teacher Guide and Pacing: the plan for each day, what to print and how to grade
- Skills map: which standards each day teaches
01 Present
- One editable PowerPoint deck for all four days, 28 slides, with speaker notes
- Slide script: the speaker notes, printed
- Bell ringers: a short warm-up for each day
02 Student Handouts
- Guided notes: one packet for all four days, in PDF and editable Word. Students fill in the blanks during the slides, with the word bank on the page
- Vocab slip: the lesson's words and what they mean, on one page
03 Labs
- Seat Map: students print and count a grid of recital seats with nested loops and book a seat from checked typed numbers in CodeGrove
- Pixel Grid: students build, color and print a grid of color names, then draw it with turtle cells in CodeGrove
04 Activities
- Grid Coordinates: students mark and name cells on a paper grid, trace a nested loop and read a 3D list, on paper with computers closed
- Quiz task: students find the first full row of seats in CodeGrove, working alone, and then take the lesson quiz
05 Assessment
- Exit tickets: quick questions that show who needs more help
- Lesson quiz: 8 multiple-choice questions and 2 written answers about all four days, on paper
06 Answer Keys
- 6 answer key files: a key for each day (its bell ringer, notes and exit ticket) and the activity and lab keys, plus the quiz key
Digital: Google Forms™ + Google Slides™
- 5 Google Forms™ of the exit tickets and the quiz, ready to copy into your Drive
- The multiple choice grades itself, and you grade the written answers
- A Google Slides™ copy of the deck, with the same slides and speaker notes, for Google Classroom™
- Give a Form that asks students to read code only on school-managed Chromebooks in locked mode, and use the paper version on other devices
Online: CodeGrove
- In CodeGrove: the labs on Days 2 and 3 (Seat Map and Pixel Grid) and the quiz task on Day 4, on a computer or tablet for each student
- Free to use, with no accounts, sign-ins or installs
Why teachers love this lesson
Row first keeps every cell easy to findStudents mark cells on paper and then use grid[row][col], so the first index always picks the row.
Nested loops can print, count and drawOne loop walks the rows and a loop inside it walks each cell. Students use that idea for a seat map and a pixel grid.
Print and digitalEvery page is a print-ready PDF, and the Google Forms™ and Google Slides™ let you teach the same lesson in Google Classroom™.
Real online labsStudents write and run real Python in CodeGrove, our in-browser code lab, on a computer or tablet, with no accounts or installs.
A key for every pageEvery day has its own answer key, and every written question has a sample answer and what to look for.
Every day fits a 45-minute classEach day's plan is timed activity by activity against real reading and writing speeds.
What Teachers Say
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How do I get the files after I buy?
Instant download right after checkout: PowerPoint and Word files you can edit, print-ready PDFs, and links that copy the Google Forms™ and Google Slides™ into your Drive.
Can I buy the whole unit or course instead?
Yes. This lesson is part of the Unit 3 bundle and the complete Python Programming 2 course. Both cost less than buying the lessons one at a time.
Is this AP Computer Science?
No. It is a full-year, non-AP second course in Python for grades 9 to 12. For AP, see our AP Computer Science A and AP CSP courses.
What should students know before this lesson?
Students know list methods, the loop patterns, how to write a function, and how print() uses end.
Do students need computers?
Yes, on the CodeGrove days. Each student needs a computer or tablet that's online, and CodeGrove needs no account or install. The bell ringers, notes, exit tickets and quiz are on paper.
What formats are the files in?
Every page is a print-ready PDF. The slides are an editable PowerPoint and the guided notes an editable Word file. The exit tickets and the quiz also come as Google Forms™, and the deck as Google Slides™.
Which standards does it cover?
Written for Florida's Intermediate Programming course (9007220). The skills map in the lesson shows which standards each day teaches.