Subjects
A subject is one thing you are studying for — its index, the boards that index builds, and the examiner who writes and marks them.
A subject is one thing you are preparing for: a qualification, a course, a single paper. It holds three things and everything else in the app hangs off one of them — an index of what the subject covers, the boards built from that index, and the examiner who writes and marks what those boards produce.
You get your first subject when you sign up. The wizard asks what you are studying, drafts an index for it, and lets you strike out anything that does not apply before you confirm. After that, new subjects come from + New subject, in the subject switcher on any dashboard or on the subject picker you land on when you sign in.
One subject, one examiner. Set it from the strip at the top of the subject's dashboard — see the examiner. Boards can be shared with other people; see sharing.
Index#
The index is the subject's contents page: parts, and topics inside them. It is written before there is a single note, and it is also the navigation — the same list appears in the megamenu on every board's bar, so the way to another board is the list of what the subject covers rather than a search box.
The wizard writes an index and no boards at all. Every entry starts planned: a name, with nothing behind it. Tapping a planned entry builds its board and takes you to it, empty, with the ways to fill it — upload a PDF and pick the pages, paste or dictate into the scratchpad, write a card by hand, or have a first pass written from the topic name alone. Tapping an entry that already has a board just goes there.
That is the whole loop: an index entry is a promise, and a board is what it becomes.
- Angular velocity ω = 2π/T = 2πf, in radians per second
- Linear speed v = ωr — the same ω gives a bigger v further out
| Case | What supplies the centripetal force |
|---|---|
| Ball on a string, horizontal circle | Horizontal component of the tension |
| Car on a flat bend | Friction between tyres and road |
| Satellite in orbit | Gravitational attraction |
Acceleration points at the centre, not along the path: a = v²/r = ω²r. Speed can be constant while velocity is not, because direction is changing.
- F = mv²/r = mω²r, and it is always a real force doing the job — tension, friction, gravity, the normal contact force
- There is no extra outward force on the object; centrifugal force is what the rotating frame looks like from inside it
Each part carries a colour, drags into order, and shows how many of its entries are built. Long names wrap rather than truncate — the index is what you navigate by, so it is never ellipsed.
Extend#
An index written before you started is an index written before you knew what the subject was. Two ways to grow it, both on the strip above the index.
By hand. + Add on the strip appends a part; + topic under a part adds an entry to it. Parts and entries both drag, and nothing moves until you let go.
Suggest missing topics is the one AI pass over the index. It reads the parts and topics you already have and proposes two things: topics the index is missing, filed under the part they belong in (a part it names that you do not have yet is marked new part), and a home for any board that no subject's index claims. There is an optional steer — "cover paediatric presentations", "assume I have done the statistics" — and it is worth using; without one the proposal is only as specific as the index it read.
Everything comes back ticked. Untick what you do not want. Nothing is written until you press Apply, so the proposal is not a change, and a topic your index already has is never proposed twice.
Beside it, History keeps restore points of the index — its name and its list, nothing else. Restoring rewrites those two and deletes nothing: a board the restored index no longer lists falls into Your boards with its notes, cards, papers and lectures intact.
Archive#
Archiving a subject takes it off the front page and keeps everything. Two questions come first — did you pass, and how useful was the subject to you — and you can skip both; nothing is written to the subject either way.
An archived subject sits under Archived subjects on the picker, and from there:
- Unarchive puts it straight back.
- Delete schedules it: a 90-day countdown shown on the row, cancellable on any day of it.
- Delete now is immediate, and it takes the boards no other index claims with them — their notes, cards, papers, lectures and audio. The number of boards is in the confirmation because that is the part nothing can undo. A board another subject's index also claims stays where it is.
Boards archive on their own clock and their own terms: an archived board is restorable for 90 days from Your boards, then deleted.