Felt: exercises from your notes, marked properly

How a course gets made

Felt on Mac: lecture PDFs dragged onto the course author

1. Drop your files on the author

PDF, Word, text, images, or just a topic. Slides go in as PDF. A short form asks what the course is for, which level, how big, and which exam if any.

Felt course view: Organic chemistry, Lecture 7, 3 files checked, Unit 1 Alkenes

2. Get a course

Units of short lessons, then exercises. Every numeric answer key is computed by Felt from the exercise's formula, never typed by the model. The validator sends anything that fails back to the author to fix. English by default; pick another language in the form.

3. Practise daily

Today's plan is one lesson to continue plus a review mix of what's due. Spaced repetition decides what is due. No lives. A speed target appears in drills once you've mastered a skill, and you can switch it off.

½, 0.5 and 1/2 are the same answer.

Numbers are marked with a tolerance, and the unit is optional: 28 and 28 g/mol both count. Decimal commas, 2^3, √ and $40 are all read. If Felt can't read what you typed, it says so instead of marking it wrong.

The checker is separate from the model that writes the course. Felt computes every numeric key from the exercise's own formula; if the author's stated answer disagrees, the validator flags it and the author has to fix it. "Ask why" is there on correct answers too, in case a key wrongly accepted you.

Felt practice screen: 28 g/mol for the molar mass of ethene marked Nice — 28 g/mol. 28 alone counts too.

Felt practice screen: Simplify 2/4, answer 1/2 marked Nailed it, with ½, 0.5 and 1/2 all accepted — ½, 0.5 and 1/2 all count.

Long problems are marked line by line.

A multi-step problem is a ladder of rungs. You get credit for each rung you got right and for following through correctly from an earlier slip, the way an examiner gives method marks. Common slips are named without AI: wrong sign, fraction upside down, off by a power of ten. Retry and the numbers change.

When you miss one, "Ask why" opens the Coach with that exact exercise attached. It answers about line 3.

Felt: Which step is wrong? Four lines of a moles calculation, line 2 chosen, Not quite, correct answer line 3, buttons Continue and Ask why — A "which step is wrong?" question. Line 3 was the mistake.

Felt Coach panel answering: Line 3 flips the formula. Moles are mass divided by molar mass — Coach, with the exercise attached.

Stuck on a term? Select it.

Select any text in a lesson and this menu appears. Terms from the course glossary answer instantly, without AI.

If the answer was useful, one more tap turns it into a practice question in your review queue. Answers you save come back free next time.

Unit 1 · Alkenes · Lesson 2

Why ethene is reactive

The double bond holds two shared pairs. One of them is a π bond, which sits above and below the plane of the molecule and is weaker than the σ bond. That is the pair that breaks first in an addition reaction.

Figures you can move.

A lesson can include a plot, a bar chart or a diagram. Move a slider or drag a point and the readouts update. Scenes show before and after, and parts of a figure can stay hidden until you have answered.

Tested so far on university physics, maths, statistics, chemistry and genetics. Name your exam in the form and the author writes to it; there is no syllabus list yet.

MathsPhysicsChemistryStatisticsGeneticsPoker, where Felt began

Income

+12%

Studying is free. The AI that writes and coaches is paid.

Free

All the practice.

Built-in courses, lessons, drills, review
Glossary and saved answers
25 quick "what's this?" questions a week
One short course of your own, to try the author
Progress on every device once you sign in

Plus

$9.99/mo

$79.99 a year. For one subject at a time.

Everything in Free
3 course credits a month, one standard course each
Coach chat, up to 15 messages a day
Unlimited quick questions
Extra credit $1.99, or 5 for $7.99

Pro

$19.99/mo

$159.99 a year. For a full course load.

Everything in Plus
10 course credits a month, large PDFs
Coach up to 25 messages a day
Full-size courses without a ceiling

Bring your own Anthropic key: $3.99 a month or $39 once.

Every AI feature without limits, billed by Anthropic to you. AI requests go straight from your device to Anthropic; Felt never sees your key.

Prices in USD before launch. Stores show them in your currency.

Before you sign up

Why not ask a chatbot to quiz me?

A chatbot marks your answer with the same model that wrote the question, and it will happily agree with a wrong one. Felt marks by fixed rules: units and tolerance, equivalent forms like ½ and 0.5, credit per step. It also keeps a review schedule across weeks, which a chat does not.

What does "checked" actually mean?

Each exercise has a type: a choice, a number with a tolerance, or a ladder of steps. The checker grades by that type's rule. Numeric keys are computed by Felt from the exercise's formula; a hand-typed key is a validator error the author must fix.

Can the AI still teach me something wrong?

Yes, in lesson text, and a wrong formula gives a consistent wrong key. A second model fact-checks each new course, but it can miss things. If an answer can't be computed, Felt says "can't grade this one yet" instead of guessing. Every exercise has a "this is wrong" button, and the Coach is one selection away.

Which subjects work now?

Anything with numeric, multiple-choice or step-by-step answers. Essays and open-ended answers are not graded.

When do iPhone, Android and Windows arrive?

Targets: Mac in December 2026, iPhone in January 2027, Android and Windows in the months after, then a web player for shared courses. Dates move if Apple or payment approval does.

Where is my data?

Courses are plain files in a folder you own, and progress stays on your device. Signing in syncs them through Felt's servers in the EU. To write a course, the text of your files goes to Anthropic's API, which does not train on it. With your own key it goes straight from your device.

Felt turns your notes into exercises and marks them properly.