How Fathom works

Syllabus. Each subject’s structure (sections, topics and learning objectives) was transcribed from Cambridge’s official syllabus document and then checked against it line by line in a separate pass. Objectives are written in our own words, keeping every technical term and condition; the official document is always the final word.

Lessons and questions. The current lessons were drafted with AI from the official syllabus, then fact-checked and reviewed by separate, independent AI passes that re-derived every answer. Every lesson is also checked automatically: the maths must render, every question must be placed straight after what it tests, and every answer key must pass our own marking code. All questions are original; we don’t copy Cambridge past papers.

Each lesson shows how it was checked:

• AI-drafted, independently checked · not yet teacher-reviewed: everything above, but no qualified teacher has signed it off yet.
• Teacher-reviewed: checked by a named, qualified teacher. Nothing carries this label yet.
• Draft: not checked. Drafts aren’t meant to reach students; if you see one, treat it with care.

You can see which syllabus objectives have lessons on each subject’s coverage page, for example Computer Science coverage.

Quick-check answers are marked by ordinary code on our server, not by AI, so the same answer always gets the same result.

• Numbers are compared with a tolerance. Fractions and exact forms like 7/2 or 2√5 count, significant figures are checked when a question asks for them, and units are checked by what they mean, so m/s, m s⁻¹ and ms^-1 are the same, and 50 cm is accepted for 0.5 m.
• Algebra is checked by evaluating your expression at many points, so any equivalent form is accepted.
• Short answers ignore capitals, spacing and punctuation but not spelling, because near-misses are often different answers (alkane and alkene). If your words don’t match, you compare with the model answer and mark yourself.
• Explain-in-your-own-words questions are self-marked against key points. Self-marked answers count for half when we work out your progress.

XP rewards learning, not clicking. It is worked out on our server, never taken away, and you can hide it in Settings at any time.

• Right on your first try: 10, 15 or 20 XP by difficulty (half for partly right). Missed it? Get it right on another day: 5. A retry straight after the answer was shown, or answering something you already got right, earns nothing, so points can’t be farmed.
• A review answered while it’s due: 10 (5 if partly right). A review session of 5 or more due questions in a day: +15. A question you once missed, now right in review: +5.
• Finishing a lesson with every check answered: 20 (+10 if every answer was right first time). Skipped a check? The lesson still counts as finished, and its XP arrives when you answer the rest. Every lesson in a topic finished: 50. Every objective in a topic Secure: 30.
• Combos (new right answers in a row): +5 at 3, +10 at 5, +15 at 10 and every 5 after. Reaching your daily goal: +10.

Levels get a new title every five: Curious, Explorer, Problem Solver, Sharp Mind, Examiner's Nightmare, Legend. There are 18 badges, all for real progress, and no leaderboards: the only person you’re compared with is you last week.