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Learn computer science.
Short study sessions that explain one idea properly, show it in a simulation, then check you got it. Mapped to the College Board course and exam descriptions, written from scratch.
How a session works
01
Learn
The answer comes first, then the explanation with an original figure, in the words the CED uses.
02
See it
Simulations let you run an attack, then switch sides and detect it.
03
Checkpoint
Self-marking questions, each with the reason the answer is right. Your score stays on your device.
Courses
AP® Cybersecurity
Networks, devices, applications and data: how attacks work and how defenders stop them.
AP® Computer Science A
Java from first class to free-response questions.
AP® Computer Science Principles
The big ideas of computing, data and the internet.
IB Computer Science
Theory, programming and the internal assessment.
Who writes this
Written by computer science educators with CCNA and CEH certifications. Every page is checked against the official course and exam description before it goes live, and every checkpoint answer is worked out independently.
No sign-up, no ads, no tracking cookies. Anything the site remembers, like your checkpoint scores, is stored only in your browser.