From hard books to engaging lectures
Upload a textbook or any difficult book. Get it back explained at your level, read aloud, with a drawing for every idea.
- EPUB · FB2 · PDF · DjVu
- Five levels of depth
- Free sample first
- 1Upload the bookEPUB, FB2, PDF or DjVu. Scanned pages are recognised.
- 2Choose your settingsLevel, language, manner of the lecturer, drawing style, voice, your own examples.
- 3Try it freeThe first five minutes, complete with voice and drawings.
- 4Get your lecturesThe whole book or just the chapters you need. You see the price before anything is made.
Drop your book here
EPUB, FB2, PDF, DjVu or TXT, up to 200 MB
Your file stays private
As if that part of the earth, where the ship is, was truly moved toward the east, with a velocity of 10010 parts; while the ship itself, with a fresh gale, and full sails, is carried towards the west, with a velocity expressed by 10 of those parts; but a sailor walks in the ship towards the east, with 1 part of the said velocity; then the sailor will be moved truly in immovable space towards the east, with a velocity of 10001 parts, and relatively on the earth towards the west, with a velocity of 9 of those parts.
Motion then splits in two.
On a ship under sail, a passenger sitting in a cabin keeps the same part of the ship, and so is at rest relative to the ship.
Let the stretch of earth under the ship move truly eastwards with ten thousand and ten parts of speed, let the ship sail westwards with ten parts, and let a sailor stroll eastwards on deck with one part.
Speeds along one line add, each measured from what carries it: ten thousand and ten, take away ten, add one, gives ten thousand and one parts eastwards, the sailor's true motion.
Relative to the earth, the earth's share drops out: the ship's ten westwards against the sailor's one eastwards leaves nine parts westwards.
The same sailor rushes east through space while drifting west along the shore.
- Upload the bookEPUB, FB2, PDF or DjVu. Scanned pages are recognised.
- Choose your settingsLevel, language, manner of the lecturer, drawing style, voice, your own examples.
- Try it freeThe first five minutes, complete with voice and drawings.
- Get your lecturesThe whole book or just the chapters you need. You see the price before anything is made.
What we do with your book
Your book, page 14
The focal length f′ of a system is the distance from its rear principal plane H′ to the rear focal point F′. For a thin lens in air it is determined by the radii of curvature r₁, r₂ of its surfaces and the refractive index n of the glass: 1/f′ = (n − 1)(1/r₁ − 1/r₂).
Your lecture
A lens is stronger when its glass is denser and its surfaces are more curved. Take ordinary glass, in which light travels one and a half times slower than in air, and curve both sides like a ball twenty centimetres across. Work it through and the focal length comes out at about ten centimetres: sunlight gathers into a point a palm’s width behind the lens.
Question: denser glass, same shape: where does the light gather?
How much detail you want
The same paragraph at five levels. Before anything is made, you choose a level on a paragraph from your own book.
Hard books, made into lectures
Real books the product has made into illustrated audio lectures: every level, three languages, one voice. Open one and listen.
PricingPay for what you make
The sample is free. After that the price depends on how much text is retold and how many drawings are made, and you see it before you start. Every book is read by a studio voice. Top up a balance and spend it book by book.
About 8 hours of lectures and 502 drawings. A rough figure for level 3. The exact price is shown before anything is made, and the first five minutes are free.
Upload a bookFree sample first · the price before anything is made · your file stays private
Examples from your world
Say who you are, in a few words: a cyclist, a driver, someone who plays football or space games. The examples are rewritten for you, and each one is marked in the text.
Without a word about you
To leave the Earth for good, a body has to start at about 11.2 kilometres a second. Gravity slows it all the way up, but it weakens with distance, so what it can take back is a fixed amount. Newton pictured it as a cannon on a high mountain: fire gently and the ball falls, fire at 8 kilometres a second and it circles the Earth, fire at 11 and it is gone. Start faster than that and the body keeps moving away for ever.
With your words: “I ride to work, there is a long hill on the way.”
To leave the Earth for good, a body has to start at about 11.2 kilometres a second. Gravity slows it all the way up, but it weakens with distance, so what it can take back is a fixed amount. From your context It is your hill on the way to work, coasting without pedalling: too slow at the bottom and you roll back, fast enough and you crest it. The Earth’s hill never ends but keeps getting flatter, and 11.2 km/s is the speed at the bottom that carries you over it. Start faster than that and the body keeps moving away for ever.
An example on escape velocity. The ribbon is only on the page: the voice reads the lecture without it.
Make it stick
Add questions after each part, worked examples and a pointer back to the page. Each is optional. Try them here.
Questions after each part
Check you followed, in a minute.
You swap a lens for one of the same shape made of denser glass. What happens to the point where sunlight gathers?
Worked examples
See the method applied, then try one.
Where the sunlight gathers From the book
Ordinary glass, in which light travels one and a half times slower than in air. Both sides are curved like a ball twenty centimetres across. How far behind the lens does sunlight gather?
Back to the book
Know which pages to cite or reread.
Chapter 2. The thin lens · pages 41–44
Starts at: The focal length f′ of a system is the distance from its rear principal plane H′ to the rear focal point F′…
Every part says which chapter and pages of your book it retells. Cite the book, not the retelling, and open the original where it matters.
Open in the book →An example. Yours are written from your own book, and a second model answers every question before you see it. Available in the player
One style of drawing, for the whole book
Five hard passages, five styles, every drawing made by our stage. Pick one style and every scene of the book follows it.
One book, different jobs
A student before an exam and an engineer before a deadline need the same hard book in different ways. Pick the one closest to you.
StudentsThe textbook of your course, explained so you can follow it tonight.Learn more
Engineers and specialistsThe main reference of your field, at exactly the depth today’s task needs.Learn more
ResearchersGet into a neighbouring field without losing a month to its textbook.Learn more
TeachersFive different explanations of a hard chapter before you explain it yourself.Learn more
Curious readersThe great hard books you always meant to read, finally from start to finish.Learn moreRead, watch or listen
Voice, drawings and text in any combination. Switch whenever you like.
Two slits, one electron at a time
Fire electrons at a wall with two narrow slits, so slowly that only one is ever on its way. Each lands on the screen as a single dot, like a tiny bullet. But after thousands of dots, stripes appear: the pattern waves make when they pass both slits and overlap. Close one slit, or watch which slit each electron takes, and the stripes vanish. Whatever an electron is on its way, it behaves as if it went through both.
Fire electrons at a wall with two narrow slits, so slowly that only one is ever on its way.
On a computer
The drawing on the left page, the text on the right, the sentence being read in full ink.
On a phone
The drawing on top and the current sentence below it. Or just the voice, on a walk.
As files
Take it with you: MP3, MP4, EPUB, FB2, PDF.
Questions
Which books work?
Textbooks, science and engineering, and any demanding non-fiction: philosophy, economics, medicine, history. Formulas are welcome, and so are books that are hard in their ideas rather than their maths.
Which formats?
EPUB, FB2, PDF, DjVu and plain text, up to 200 MB. Scanned pages are recognised, about a second a page; you can make the free sample from the first pages while the rest is read, and the whole book once it is done.
What does it cost?
The first five minutes of any book are free, with the voice and the drawings. After that you pay per book from a prepaid balance: about $0.14 a page without drawings and $0.20 with them, read by a studio voice (a book in English at level 3; another language costs a little more or less). The exact price is shown before anything is made, and an unused balance is refunded on request within 14 days.
Do I pay to listen?
No. Every lecture is read by a studio voice, a recorded narration made and checked word by word, and the voice is in the price of the book: listening, in the player or as MP3 and MP4, costs nothing more.
Which languages?
A book can be told in its own language or in another one. The samples in the library come in English, Russian and Spanish, at every level; the site itself speaks nine languages.
Is it the author’s text?
At the first level, yes: the book is read as written. At the other levels it is retold in new words, keeping the order, the conclusions and the results; if you ask for it, every part says which pages of the book it retells.
Is my book private?
Yes. Your uploads and lectures are visible only to you. You can share a lecture by link if you want to; the link lets people listen and read, not change or download anything.
Can I come back later?
Every book stays under My books. Return any time to change the settings, go further into the book, or add a download: EPUB, FB2 or PDF, and MP3 or MP4 when the book was made with a studio voice.
What if a part comes out wrong?
A few drawings and parts of a finished book can be made again, free: say what was wrong and the new version is written with that in mind. A job that failed on our side is charged only for what was made.
Where can I see it before I upload?
The samples are real books made into lectures and left as they came out: open one, pick a level and a language, and listen.
How long does it take?
Reading the book takes about a minute, a scan a few minutes more. The free sample is ready in a few minutes; for a whole book the text is written first, part by part; the first parts are drawn and voiced at once, the rest as you reach them.
Do I have to do the whole book?
No. Choose the chapters or the pages you need and pay for those. You can come back for more later with the same settings.
What is a level?
How much of the book stays. Level 1 is the text word for word; level 2 keeps every formula, term and argument and explains each; level 3 puts the hard parts in plain words; level 4 is ideas through examples, no formulas; level 5 is the gist of the whole book in about an hour. You try a level on a paragraph of your own book before anything is made.
May I upload a book I bought?
Yes, if the law lets you have your copy processed this way, or the book is your own, in the public domain or under an open licence; checking that is up to you. Your uploads stay private and are never used to train models.
How do I pay? Is there a subscription?
By card, in US dollars, tax included: a one-off top-up of your balance, or a monthly or yearly subscription that adds a little more to it each period. Organisations can pay by invoice. A subscription can be cancelled any time; the balance stays.
Are formulas read aloud properly?
Yes. Each formula is written twice, as it is printed and as it is said, and the voice reads the spoken form. With a studio voice every paragraph is recognised back and compared with the text.
Which voices are there?
One of 30 studio voices, women’s and men’s, in each of the 42 languages a lecture can be told in. You hear each one before choosing.
Which drawing styles are there?
Six: graphic ink, poster, white on black, pencil, ink on paper and the old textbook, with 13 faces for the lettering. You also choose how many drawings: none, one a part, or up to one a minute.
Can the examples be about my own work?
Yes. Say in a few words what you do or use, and the examples are rewritten for you and marked in the text; the voice reads them like the rest.
What study aids are there?
Questions after each part, answered by a second model before you see them; worked examples and problems to try; and the chapter and pages each part retells. They live in the player, not in the files.
Can I choose how the lecturer talks?
Yes, eight manners, from a patient tutor to a rigorous professor or a storyteller. You hear each one read a paragraph of your own book.
Does it make things up?
A second model compares every retold part with its passage before you see it; sentences that say what the book does not are rewritten, and the part is checked again. Ask for page references and every part says which pages it retells, so you can open the original.
Can I change my mind later?
Yes. Another level, another language, another voice or another look is a new version of the same book, priced like the first. Study aids come with a new version too.
What if my balance runs out half-way?
It cannot: the price of a job is set aside before it starts, so a job that started will finish. If it stops for a reason on our side you are charged only for the parts that were made.
Can I share it with my students?
Yes. A link lets anyone listen and read the lectures in their browser without an account. For a class or a school write to us; we issue invoices, payable within 30 days, and top-up codes.
Does it work on a phone?
Yes, in the browser, with nothing to install: the drawing on top and the current sentence under it, or just the voice. MP3 files play anywhere.
How do I delete a book or my account?
A book goes from My books, with its lectures and files. To close the account write to us and everything is deleted as the privacy policy describes; an unused balance you paid for is refunded within 14 days of the top-up.
How do I reach you?
Write to hello@lecturized.com. A person reads every message, and we answer within a day.