Big Idea 5 — Impact of Computing
How computing changes society: its benefits and harms, who has access, how bias creeps in, how people collaborate online, what the law and ethics require, and how to stay safe. This Big Idea is worth 21–26% of the AP exam. Each section ends with a short practice set — click "Show answer" to check yourself.
Big Idea 4 — Computer Systems and Networks
How the Internet moves data, why it keeps working when parts fail, and how parallel and distributed computing solve problems faster. This Big Idea is worth 11–15% of the AP exam. Each section ends with a short practice set — click "Show answer" to check yourself.
Big Idea 3 — Algorithms and Programming
The heart of AP CSP: variables, lists, conditionals, loops, procedures, libraries, simulations, algorithm efficiency, and the limits of computing. This Big Idea is worth 30–35% of the AP exam and supports the Create Performance Task. Code uses AP exam pseudocode (lists start at index 1). Each section ends with a short practice set — click "Show answer" to check yourself.
Big Idea 2 — Data
How computers represent data with bits, how data is shrunk for storage and transmission, and how people and programs turn raw data into useful information. This Big Idea is worth 17–22% of the AP exam. Each section ends with a short practice set — click "Show answer" to check yourself.
Big Idea 1 — Creative Development
How computing innovations are made: working with others, understanding what a program does and why, following a design process, and finding and fixing mistakes. This Big Idea is worth 10–13% of the AP exam and also underpins the Create Performance Task. Each section ends with a short practice set — click "Show answer" to check yourself.
Beneficial and Harmful Effects
Computing innovations affect society, culture, and the economy — often in ways their creators did not plan.
- An innovation can have both beneficial and harmful effects at the same time, and the effects can differ for different groups of people.
- Effects may be intended (a messaging app connects people) or unintended (it also spreads misinformation or affects mental health).
- The same innovation can be used for good or bad purposes (dual use) — for example, facial recognition can find missing people or enable surveillance.
- Rapid sharing of information, automation, and data collection bring benefits (access, convenience, new jobs) and risks (privacy loss, job displacement).
- Developers should consider a wide range of users and possible effects, not just the main purpose.
1. Give one beneficial and one harmful effect of social media.
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2. What is meant by an "unintended effect" of an innovation?
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Digital Divide
The digital divide is the gap between people who have access to computing devices and the Internet and those who do not.
- It can exist between countries, regions (urban vs. rural), income levels, age groups, and other demographic groups.
- Access affects education, job opportunities, healthcare, and civic participation.
- It can increase existing inequalities: those without access fall further behind as more services move online.
- Ways to reduce the gap: public libraries and Wi-Fi, low-cost devices and plans, school programs, and government investment in infrastructure.
- Technology can affect different groups differently based on their access, skills, and resources.
1. A student has no home Internet and cannot complete online homework. Which concept does this show?
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2. Suggest one way to reduce the digital divide.
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Computing Bias
Bias is a tendency or prejudice toward or against something, often unfairly. Computing innovations can reflect or even amplify human biases.
- Sources: biased or incomplete training data, assumptions made by programmers, and design choices that overlook certain users.
- Examples: a face-recognition system trained mostly on certain faces works poorly for others; a hiring algorithm trained on past decisions repeats past unfairness.
- Because programs seem objective, biased results can be mistaken for neutral facts.
- Reducing bias: use diverse and representative data, test with many types of users, build diverse teams, and regularly review results.
1. A voice assistant often misunderstands some accents. What is a likely cause?
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2. Give one way to reduce bias in an algorithm.
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Crowdsourcing
Crowdsourcing means getting ideas, work, data, or funding from a large group of people, typically online.
| Type | Example |
|---|---|
| Knowledge sharing | Wikipedia, open-source software |
| Citizen science | Volunteers classify galaxies, count birds, or report observations |
| Crowdfunding | Many people give small amounts to fund a project |
| Problem solving | Online contests or games that solve research puzzles |
- Benefits: diverse perspectives, large scale, speed, and lower cost; can solve problems hard for one group alone.
- Challenges: varying quality, errors or deliberate misinformation, and needing a way to check and combine contributions.
1. Is a project that raises money from thousands of online donors an example of crowdsourcing?
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2. Give one benefit and one challenge of crowdsourcing.
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Legal and Ethical Concerns
Using, sharing, and creating digital content raises legal and ethical questions.
- Intellectual property — creations such as code, music, images, and writing belong to their creators. Copyright gives creators legal control over how their work is copied and used.
- Plagiarism — presenting someone else's work as your own. Always cite sources.
- Piracy — copying or sharing protected material without permission.
- Creative Commons — licenses where creators allow others to use their work under stated conditions (for example, give credit, or no commercial use).
- Open source — software whose code is freely available to use and modify; open access — freely available research and content.
- Digital data is easy to copy and share, which makes enforcing ownership difficult.
- Ethics goes beyond the law: just because something is legal doesn't mean it's fair or right.
1. What does a Creative Commons license allow?
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2. A student copies an online article into a report without credit. What is this?
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Safe Computing
Keeping personal information and systems secure is a shared responsibility of users and developers.
- Personally identifiable information (PII) — data that can identify you (name, address, phone, ID numbers). Online activity can be tracked and combined, creating privacy risks.
- Authentication — verifying who you are. Use strong passwords and multi-factor authentication (MFA), which needs two or more of: something you know (password), have (phone), or are (fingerprint).
Encryption
- Encryption scrambles data so only authorized people can read it; decryption reverses it.
- Symmetric encryption uses one shared key for both. Public-key (asymmetric) encryption uses a public key to encrypt and a matching private key to decrypt.
Common threats
| Threat | Description |
|---|---|
| Phishing | Fake emails or sites trick you into revealing information |
| Malware | Harmful software (viruses, ransomware, keyloggers) that damages or spies |
| Keylogging | Secretly records what you type |
| Rogue access point | Fake Wi-Fi hotspot that intercepts data |
- Protection: antivirus/anti-malware, software updates, careful clicking, and using secure (HTTPS) connections.
1. What makes multi-factor authentication stronger than a password alone?
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2. An email claiming to be from your bank asks you to enter your password on a linked page. What attack is this?
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3. In public-key encryption, which key decrypts a message encrypted with someone's public key?