Where everything starts. Ask him anything, work through a topic, or get your answers marked. When you open a new chat, pick one of four ways in:

Best for: anything you're stuck on, right now. One revision session, one chat — it keeps things easy to find later.

Tap the camera in the message box and photograph a question, your working, or both — up to four pages at once. Dexter reads the page and marks what you wrote. Snap it on your phone and it lands on your computer if that's where you're working.

Best for: a question from a textbook or worksheet you can't type out. He can't see what you've drawn onto a printed diagram — describe mechanisms in words and he'll coach you on that instead.

Live sessions with Rich, where you can ask him questions directly and get an answer there and then. He uses these mostly on skills — the things you need to be able to do rather than remember. Past sessions are there to watch back.

Best for: the stuff that's easier shown than written — calculations, mechanisms, working through a method.

Every conversation you've had, saved and searchable, on any device. Pick one up where you left off.

Best for: finding that explanation you know he gave you three weeks ago.

Rich's own notes on every topic on the AQA specification — written for the exam, not copied out of a textbook. Dexter will send you straight to the right page mid-conversation, or browse by topic yourself.

Best for: catching up on a lesson you missed, or priming a topic before you meet it in class. Reading on its own doesn't stick — always finish with some questions.

Decks for every topic. Flip the card, sort it into Correct or Incorrect, and your scores go into My Progress automatically.

Best for: the things you need to recall — definitions, colours, observations, equations. Two or three sessions a week beats one long one, because the spacing is the whole point. Flash cards alone will cap your grade: they won't teach you to apply anything.

A map of every organic reaction. Click a functional group and see what it turns into, with the reagents, the conditions and the mechanism name.

Best for: the links between functional groups — which is exactly what synthesis questions test. Use it right through the year; it can't be crammed in the last fortnight.

A 20-minute burst on one sub-topic, in three parts: Recall (a quick knowledge check), Skills (worked, then guided, then on your own), and Synthesis (a harder exam-style question).

Best for: a top-up on one thing, and a different way of being tested — especially before a topic test, and during the year while full papers are still off the table. Never use it on its own; it's one tool of several.

Build your own test: pick the paper, the topics and the length, and you get a proper test with a mark scheme and a score that counts.

Best for: when you want a real test rather than a question or two in the chat. With Catalyst, it's what you use to prepare for a mid-year topic test.

Sit a real AQA past paper, mark it yourself against the real mark scheme, then enter your marks here. You get a full report on what went well and what didn't, and your revision priorities are built from it.

Best for: the single most powerful thing on here — the moment you've finished the content for a paper, sit one. Timed, closed book, and marked honestly with no grace given, because the examiner gives none. Marking it yourself is half the revision: it teaches you the wording they pay for. Open book, or asking Dexter for answers mid-paper, makes the result worthless.

Where it all lands: your readiness score, your target grade, your revision priorities, and a topic-by-topic breakdown. Two things live inside it — Tests & Mocks, where you log a test that's coming up so the platform can build priorities for it, and the My Data tab, where you keep your target grade, your confidence ratings and what you've covered in class up to date.

Best for: knowing what to do next instead of guessing. The only real way to get it wrong is to ignore it and let it go stale — if My Data is out of date, Dexter is pitching at the wrong level.