Computer Education
Domain 3 tests computer literacy and the teaching of technology: hardware and software, data representation, networks and the internet, security and ethics, digital citizenship, productivity applications, and computational thinking.
Core rules and concepts
- A bit is one binary digit; eight bits make a byte. Binary place values double from right to left: 1, 2, 4, 8, 16, 32, 64, 128.
- RAM is volatile working memory; ROM is nonvolatile firmware storage; secondary storage persists without power.
- An operating system manages hardware, files, memory, and processes, and provides a user interface.
- Networks range from LAN to WAN; IP addresses identify hosts, DNS resolves names, and HTTPS encrypts web traffic.
- Security controls include strong unique passwords, multi-factor authentication, patching, backups, and phishing awareness.
- Digital citizenship covers copyright and fair use, privacy, acceptable use, and respectful online behavior.
Worked example
Convert binary 10110110 to decimal. Write place values from the right: 128, 64, 32, 16, 8, 4, 2, 1. Add only where the bit is 1: 128 + 32 + 16 + 4 + 2 = 182. Check: the leftmost bit is 1, so the value is at least 128; the sum fits below 256, as an 8-bit number must.
Traps that cost marks
- Confusing bits and bytes when stating file size or bandwidth.
- Claiming RAM stores files permanently.
- Treating HTTP as secure; HTTPS uses TLS encryption.
- Mixing relative references (A1) with absolute references ($A$1) in spreadsheet formulas.
- Assuming deleting a file securely erases it; overwriting or physical destruction may be needed.
- Reproducing copyrighted images because they are online.
Teach with a task: students convert numbers, then design a secure classroom network policy.