Subjects
A subject is one thing you are studying, with its index, its boards and its examiner.
A subject is one thing you are studying: a qualification, a course, a single paper, or something you are learning for yourself. It holds an index of what the subject covers, the boards built from that index, and the examiner who writes and marks what those boards produce.
The home page lists Your subjects, then any Shared with you (see sharing), then Your boards: boards that belong to no subject, for a one-off topic that does not need an index. Make one with New board. On the web you can file it into a subject later from its tile (Move or copy), and Suggest missing topics (below) offers it a home too. A board outside a subject uses your account's examiner.
Setting one up#
The first time you sign in, the app opens the subject wizard; I'll do this later skips it. Tell it what you are studying and, optionally, what it is for. You can add a course outline, syllabus or book contents, as a PDF or pasted text, and the index will follow it (a scanned PDF has no text to read, so paste instead). If your words could mean more than one thing, it asks which you meant.
It then drafts an index. Pick how much to cover (The basics, Standard or Extended) and whether to start with sections and topics or sections only, strike out what you are not studying, and press Use this index. A whole degree can be one subject, with a section for each unit. Later subjects come from + New subject, on the home page or in the subject switcher.
Nothing is final. Rename a subject from the pencil on its card (on the iPhone, its ⋯ menu), and grow its index whenever you like.
The dashboard#
A subject's dashboard has three tabs. Index is the subject itself (below). Practice picks sections across its boards for a drill, a paper or a station; see practice. Study shows how it is going: what is due, mastery and recent marks, where you left off, what needs attention, and what is waiting in each board's Sources. On the iPhone these are one screen, with Practice a row of its own.
The language pill beside the counts sets what the AI writes this subject's boards in; see languages. The examiner is matched from what you told the wizard; see the examiner.
Index#
The index is the subject's contents page: numbered sections, with topics inside them. It is also how you get around: on the web, the arrow beside a board's name opens the same list from any board.
The wizard writes an index but no boards. Every entry starts as planned: just a name. Tap a planned entry to build its board. On the web the new board opens blank and offers its ways in: let the AI write it, upload a PDF or Word document, drop material into Sources, or write a section yourself (see boards). On the iPhone the AI fill opens over the new board; go back to write it yourself. Tapping an entry that already has a board opens it, and tapping an archived one restores it.
- 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 section has a colour and shows how many of its entries are built.
Extend#
There are three ways to grow an index. Only the subject's owner can.
By hand. On the web, + Add on the strip adds a section and + topic under a section adds an entry. Drag either into order, click a section's colour chip to change it, and use the cross to take out an unbuilt entry or an empty section (on a built entry, the cross archives its board). On the iPhone, a section's ⋯ menu and a long press on an entry do the same, with Move up, Move down and Move to another section in place of dragging.
Suggestions under the box (web). Open + topic or + Add and the AI lists up to eight missing topics or sections underneath (the first time takes a few seconds). Click one, or press Enter for the highlighted one; the box stays open so you can add several. Typing narrows the list, and Enter then adds your own words. It never suggests anything the index already has.
Suggest missing topics (Suggest topics on the iPhone) reviews the whole index. It proposes missing topics under the section they belong in (a section you do not have yet is marked new section), and a home for any board no subject's index includes. Add a steer if you can, such as "go deeper on the second half of the course" or "assume I have done the statistics"; the results are more specific with one. Everything comes back selected: tap a proposal to leave it out, then press Add ticked. Nothing changes until you do.
History (web), beside it, keeps restore points of the index's name and list for 30 days. Restoring saves the current index as a restore point first, and deletes nothing: a board the restored index no longer lists moves to Your boards with all its notes, cards, papers and lectures.
Archive and delete#
Archive a subject from its card on the home page (on the iPhone, its ⋯ menu). It comes off the front page and keeps everything; its boards wait under Your boards until it is back. Three optional questions come first: did you pass (for a subject with no exam set, whether you got where you wanted to), how useful it was, and anything else. Skip and archive skips them. If the subject is shared, the people in it lose access until you unarchive it.
Archived subjects sit under Archived subjects on the home page. From there:
- Unarchive puts it straight back.
- Delete schedules deletion in 90 days. The row counts down, and Cancel deletion stops it on any day.
- Once it is scheduled, Delete now deletes it at once, with the boards no other subject's index includes and their notes, cards, papers, lectures and audio. The confirmation tells you how many boards that is. A board another subject also includes stays.
Boards can be archived on their own too: from the index, or from a loose board's tile (on the iPhone, a long press). An archived board keeps its cards, papers and lectures. Restore it by tapping its entry in the index; a board outside a subject is restored, or deleted at once, from Archived boards on the home page. After 90 days it is deleted. Archiving a board you have shared freezes it for the people in it; see sharing.