Unit 2 is roughly 17–22% of AP CSP multiple-choice content. Treat this page as the table of contents for the cluster: read it once, mark weak rows, then open the linked guides instead of rereading the same definitions in random order.
What topics are in AP CSP Unit 2?
Which skills does the College Board emphasize?
Data topics span representation, storage, compression, information extraction, and societal impacts. You should explain why machines use binary, convert small numbers, compute compression ratios, choose lossless or lossy formats with reasons, describe metadata risks, and discuss bias and privacy in plain language.
Calculation items stay small—four-bit conversions, eight-bit overflow, simple ratio arithmetic. Process items matter more: filtering a table, cleaning messy survey results, or justifying why JPEG is acceptable for yearbook photos but not for medical measurement logs.
Lists and pseudocode tracing from Unit 1 reappear inside data stories. A stem may ask how many times a loop visits elements while also testing whether you understand bytes stored per item.
How should you order a two-week review?
Week one: representation and size
Start with binary numbers so place values feel automatic. Move to bits and bytes for ASCII, file labels, and overflow. Finish the week with binary conversion drills until you can do 13 ↔ 1101 without hesitation.
Each day, answer two MCQs from the hub diagnostic or the eight-question sets on concept pages. Keep a running list of misses tagged “width,” “ASCII,” or “Mbps vs MB.”
Week two: compression through society
Study data compression until you can state both ratio and percent saved for 100 MB → 25 MB. Follow with lossless vs lossy scenarios, then metadata and big data and privacy.
End the week with the eighteen-question quiz under light time pressure, then the fifty practice MCQs across two or three sittings.
How does Unit 2 connect to Unit 1?
Where do creative development ideas return?
Unit 1 stressed collaboration, documentation, and testing. Unit 2 asks what happens to the data those programs collect. A Create Task app that logs user scores stores integers as binary; exporting results as CSV introduces metadata columns.
Mix five Unit 1 questions into every Unit 2 session via the Unit 1 hub so vocabulary from both units stays warm through May.
Where are flashcards, notes, and the cheat sheet?
Which tools fit which study mood?
Use Unit 2 notes before class for a skim, cheat sheet five minutes before practice, and sixty flashcards for vocabulary you keep missing.
The hub diagnostic is only ten questions—great for routing, not enough for exam stamina. Pair it with the full practice set once your weak-area list shrinks below three topics.
What exam traps repeat every year?
Which mistakes are worth a sticky note?
Label bits versus bytes before calculating. Check bit width before picking large decimals. Separate compression ratio from percent saved. Treat correlation as weaker language than causation. Name a benefit and a risk together on societal-impact prompts.
When a stem mentions GPS on photos, think metadata privacy, not compression. When a stem mentions repeated pixel colors, think run-length encoding.
How do Create Task and Unit 3 tie to Data?
When should you mention bytes or compression in write-ups?
If your app stores images, audio, or large logs, note file size limits users might hit on school networks. Mentioning that you exported lossless PNG screenshots for documentation but JPEG for user-uploaded photos shows you understand representation beyond the code block.
Unit 3 algorithms revisit lists while processing data. A loop that scans sensor readings still depends on how many bytes each reading consumes. Keep Unit 2 vocabulary alive while you trace pseudocode so “index out of bounds” errors connect to list length, not mysterious magic.
What should a one-page cram sheet include?
Which formulas belong on scratch paper?
Write powers of two through 128, the 2ⁿ value rule, unsigned max 2ⁿ−1, compression ratio as original : compressed, and a two-column note separating percent saved from the ratio itself. Add one lossless and one lossy example per media type: PNG versus JPEG for images, ZIP versus MP3 for archives versus songs.
On societal-impact scratch work, draft “benefit + risk + affected group” before you touch MCQ choices. That template speeds questions about loyalty cards, fitness trackers, or training data bias.
How do you know you are exam-ready for Unit 2?
Which checkpoints matter more than total hours studied?
You are in strong shape when you can teach a classmate why 111 + 1 overflows in three bits, when you can justify JPEG for a yearbook page in two sentences, and when you can explain why GPS EXIF is a metadata privacy issue without saying “the internet is dangerous.”
Checkpoint numbers help: eighty percent or higher on the eighteen-question quiz, seventy-five percent or higher on each topic column of the fifty-question set, and five correct Unit 1 mixed questions after a Unit 2 session. Missing any one checkpoint means one more targeted guide—not another passive reread of this review.