Everything in AP Computer Science Principles fits together. This is the whole system, one unit at a time.

Start here: Units 0 and 1 are complete — the big picture, then how the world becomes bits, across twenty lessons. Units 2 and 3 are complete. Everything below Unit 3 is planned but not written yet.

Signing in is optional. Every lesson works without it — it just lets me see who's finished what.

Practice tools

TOOLS

Flip drills, trace table, pseudocode viewer

Separate site

Endless practice on the two flips the exam punishes most, plus a step-through tracer and the Python ↔ AP Pseudocode viewer.

Units

UNIT 0

The Big Picture

All 5 lessons live

What actually happens when you send a photo? — Week 1

  1. 0.1  The Photo Trip
  2. 0.2  Everything is Bits
  3. 0.3  Machines Follow Instructions
  4. 0.4  The Whole System
  5. 0.5  How This Course Works
UNIT 1

Digital Information

All 15 lessons live

How does the world become bits? — Weeks 2–4

  1. 1.1  Two Symbols Are Enough
  2. 1.2  Binary ↔ Decimal
  3. 1.3  When Numbers Break
  4. 1.4  Text as Bits
  5. 1.5  Images and Color as Bits
  6. 1.6  Analog to Digital
  7. 1.7  Abstraction
  8. 1.8  Compression I: Lossless
  9. 1.9  Compression II: Lossy
  10. 1.10  Bits in Python
  11. 1.11–1.12  Mini-Project 1: Secret Messages in Bits
  12. 1.13  Rebuild the Map
  13. 1.14  Test Day (review & practice)
  14. 1.15  Flex Day: How Big Is a Minute of Video?
UNIT 2

Programming 1: Talking to the Machine

All 20 lessons live

How do we give instructions? — Weeks 5–8

  1. 2.1  Your First Real Program
  2. 2.2  Variables and Assignment
  3. 2.3  Expressions, Arithmetic, and MOD
  4. 2.4  Input and Output
  5. 2.5  Lab: Calculator Day
  6. 2.6  Strings I: Text Is a Row of Characters
  7. 2.7  Strings II: Methods and f-Strings
  8. 2.8  When Programs Go Wrong
  9. 2.9  How Software Actually Gets Made
  10. 2.10  Lab: Mad Libs (paired)
  11. 2.11  Booleans and Comparisons
  12. 2.12  Selection: if / else
  13. 2.13  elif and Nested Conditionals
  14. 2.14  Logical Operators
  15. 2.15  Lab: Decision Day
  16. 2.16  Testing, Edge Cases & Pseudocode Gym
  17. 2.17–2.18  Mini-Project 2: Quiz Bot
  18. 2.19  Rebuild the Map & Review
  19. 2.20  Test Day (review & practice)
UNIT 3

Programming 2: Power Tools

All 25 lessons live

How do we manage complexity? — Weeks 9–13

  1. 3.1  The while Loop
  2. 3.2  while vs REPEAT UNTIL
  3. 3.3  Counting Loops
  4. 3.4  The Accumulator
  5. 3.5  Lab: Loop Day
  6. 3.6  Lists I: Many Values, One Name
  7. 3.7  Lists II: Growing and Shrinking
  8. 3.8  Traversal
  9. 3.9  Canonical List Algorithms
  10. 3.10  Lab: Gradebook Day
  11. 3.11  Calling Procedures
  12. 3.12  Writing Procedures
  13. 3.13  return vs print
  14. 3.14  Procedures + Lists (the Create PT pattern)
  15. 3.15  Lab: Refactor Day
  16. 3.16  Libraries and APIs
  17. 3.17  Random Values
  18. 3.18  Lab: Random Day
  19. 3.19  Pseudocode Gym II
  20. 3.20  Test Day (review & practice)
  21. 3.21  How the Create PT Works
  22. 3.22–3.24  Create PT: Build Days
  23. 3.25  Written Responses
UNIT 4

Algorithms & Simulation

Planned

Which solutions are even possible?

UNIT 5

Data

Planned

What can bits tell us?

UNIT 6

The Internet & Computing Systems

Planned

How do bits travel and scale?

UNIT 7

Cybersecurity

Planned

How do we protect bits — and from whom?

UNIT 8

AI & the Impact of Computing

Planned

What do computers do to us and for us?

UNIT 9

Create Performance Task

Planned

Build something that's yours.

UNIT 10

AP Exam Boot Camp

Planned

Reassemble the whole system.