Your study companion · iPhone and web

parenthesis

It explains, quizzes, reviews, remembers, waits, and keeps up.

One to one teaching is the oldest thing that works, and the least available. Parenthesis learns how you think, holds the whole term in mind, and hands back structure instead of answers.

no account · free to try
Free to start · iPhone and web · Android coming soon
Asking under
Chemistry
5 min in · session open
explain limiting reagents like i'm behind, test is friday
Friday's test, mostly. Start here: one reactant runs out first and stops the reaction. Before any maths, which one do you think it is?
Quick check
2 mol H₂ meets 2 mol O₂. Which runs out?
H₂, it has the smaller coefficient
H₂, the ratio needs 2 for every 1 O₂
O₂, there is less of it by mass
Work it out here
The kind of thing people ask
01

explain limiting reagents like i’m behind, test is friday

( ask )
02

why does the sign flip when i divide by a negative

( ask )
03

i got 14, the key says 11. where did i go wrong

( ask )
04

quiz me on the parts of a cell, five, make them hard

( ask )
05

i have 20 minutes before practice, what should i review

( ask )
06

walk me through step one, then let me try the rest

( ask )
07

what does my syllabus mean by "series", in plain words

( ask )
The mess is the input

Say it badly. That is what learning sounds like.

Half formed questions are the normal case. Parenthesis takes the mess, gives back structure, and stops one step short of the answer so the thinking stays yours.

Structure, not the answer
Ratio 2 : 3, and you have 4.0 mol of the 2 side.
Step 1 · write the ratio as a fraction, with the side you want on top.
Step 2 · multiply, and check the units cancel.
Your turn: which number goes on top? Say it and I'll check the unit.
Steps

How it works

Three things happen, in this order, and none of them require a routine you will not keep.

01

Drop in your own materials

Syllabus, lecture notes, past exams. The map of topics comes out of your files, in no fixed order, because a syllabus is not a straight line. Skip it and the app still works, it just knows less.

syllabus.pdfread · 11 topics minted
week-4-lecture.pdfread
midterm-2025.pdfread · the strongest signal
StoichiometryLimiting reagentsGas lawsThermochem
02

Study in sessions that end

Ask under a subject or from anywhere. Talk, type, or dictate. Quick checks interrupt you on purpose, and when you stop the session wraps itself and files what happened.

01Openedasked under Chemistry
02Quick checkmid-explanation, on purpose
03Quick checkthe same step again
04Wrappedfiled: 1 topic moved
( a session ends, so the week has a shape )
03

It remembers, and tells the right person

Mastery moves on evidence, not on minutes sat down. Next term it still knows where you stall. Your parent gets the week in sentences, and never the transcript.

Stoichiometry( mastered ✓ )
Limiting reagents( not yet )
One soft spot left before Friday. Here is what to ask.
( evidence, not minutes sat down )
Inside the app

Four screens doing the actual work

01

A session that argues back

Hints escalate: a nudge, then structure, then a worked parallel example on different numbers. The answer stays yours to reach. Maths renders properly, and a quick check lands mid explanation to see if the idea clicked.

Asking under
Algebra II
Midterm Oct 15
Midterm Oct 15 · Algebra II spans linear through logarithmic functions, polynomials, matrices, and series.
A quadratic has a highest power of exactly x², no higher, and that squared term has to be there.
give me one quick check on that. keep it short
Quick check
Which of these is a quadratic equation?
x³ + 2x = 0
3x² − 5 = 0
4x + 7 = 0
x⁴ − 1 = 0
quick check · spotting a quadratic
Go ahead and pick. No pressure, I'm checking whether the idea clicked.
Work it out here
5:00
Warming up · 1/6
Q1 · linear equations · level 1
What is the value of x in the equation x + 5 = 12?
x = 7
x = 17
x = 5
The ladder
Expert06
Very sharp05
Sharp04
In stride03
Finding footing02
Warming up01
( right climbs · wrong eases off )
02

Rapid fire, five minutes, on the ink

Six rungs from warming up to expert. Right climbs one, a right answer inside five seconds climbs two, wrong eases one back. The rung is re-graded on the server when the round ends, so it means something. What you miss becomes tomorrow's plan.

03

A map of what you actually know

Topics minted from your own syllabus, marked mastered or not yet from real evidence. Stage words, no percentages, no fake precision, no order assumed. Plus the tools that come off it: predicted exam, cheat sheet, focus timer.

Algebra II

Summer 2026
The map
Linear equationsSystems of equationsFactoring quadraticsCompleting the squareQuadratic formulaPolynomial expressionsExponential functionsLogarithmic functionsMatricesSequencesSeries
mastered / not yet · inferred from sessions and quizzes. No order assumed; your syllabus isn't a straight line.
Linear equations( mastered ✓ )
Factoring quadratics( getting there )
Series( not yet )
Predicted exam
from your past papers
Cheat sheet
your weak spots, one page
Focus timer
pomodoro, then a wrap quiz
Your view
Week of Jul 13

Maya, this week.

3h 20mstudying
6topics touched
steady climb
Ask which reactant runs out first, and how she knows before she calculates.
Where things stand
Stoichiometry( mastered ✓ )
Limiting reagents( not yet )
How Maya uses the companion
18 questions worked through
0 answers handed over
5 sessions wrapped · 1 open
( progress, never their sessions · by design )
04

What a parent sees, and where it stops

The week in stage words and counts: time studied, topics touched, what moved, and what to ask at dinner. Including how many answers were handed over, which is zero on purpose. Never the sessions themselves.

Why we are building it

Great teaching is one mind paying attention to one mind, for years.

Aristotle taught Alexander: one student, one teacher, years at a time. For most of history that has been a privilege. A tutor who knows where you stall, what you already believe, and when to push is the oldest technology in education and the least available one.

Parenthesis is the attempt to make it ordinary: patient on the tenth try, specific about your Friday test, honest with the person paying attention at home, and still there next term.

( a companion that grows as the student does · not an answer machine )
For parents

You see summaries, not sessions.

A study tool a student will hide is worth nothing. So the boundary is built into the software, not into a settings page: you get progress and what to ask, they keep their sessions.

Free to start · iPhone and web · Android coming soon
The weekly recap

What moved, what is still open, and what to ask tonight. Stage words and counts, so you can read it in a queue.

Co-study, on two devices

They see the question and a scratchpad. You see a hint card and what to ask next. You help without taking over, and without needing to know the chemistry.

Counts, not vibes

Questions worked through, sessions wrapped, answers handed over. If the tool ever starts doing the homework, that number moves and you will see it.

Pricing

Start free. Pay when it earns it.

Free
$0

A set amount of study each month. When you run out, the app says so and offers Pro. It never stops mid explanation.

  • Sessions, quick checks, rapid fire
  • One subject folder
  • Parent view, if you invite one
Recommended
Pro
$20per month
billed monthly

Everything, for one student who studies most days.

  • Unlimited sessions and rapid fire
  • Live voice, dictation, read aloud
  • All subjects, all study tools
  • Predicted exams and cheat sheets
  • Co-study with a parent or a friend
Pro 5x
$60per month
billed monthly

Five times the Pro usage. For exam terms, heavy voice use, or a household with more than one student.

  • Everything in Pro, five times over
  • Priority on long generations
  • Multiple students on one plan
Schools and centres
Let's talk

Colleges, schools, and tutoring centres. Cohort setup, coach dashboards, and rollout support.

  • Seats and cohorts
  • Coach and teacher views
  • Onboarding for your curriculum
Prices in USD. Cancel any time; annual saves 20%.
Questions

The ones people actually ask

Does it just give the answer?

No. Hints escalate: a nudge, then structure, then a worked parallel example on different numbers. The answer stays yours to reach, and the parent view counts how many answers were handed over.

What exactly can a parent see?

Time studied, topics touched, whether a topic is mastered or not yet, the weekly recap, and what to ask. Not the sessions. The boundary is in the software, not in a preference.

Who is it for?

Anyone from 13 up with something hard enough in front of them to want a second pass at it. One account can be both a student and a parent, which is more common than it sounds.

Do I have to upload anything?

No, and it is worth it anyway. A syllabus unlocks the topic map, dated reminders, predicted exams, and a cheat sheet aimed at your weak spots rather than the whole unit.

What happens when the free tier runs out?

The app tells you as you go, then offers Pro. Nothing you made disappears, and you keep your subjects, sessions, and map.

Can I study with someone?

Yes. Co-study pairs two devices: the student works, the partner gets a hint card and what to ask. It works the same whether the partner is a parent or a friend.

Start with one question.

Whatever you are behind on right now. Say it badly, and see what comes back.

Free to start · no card
Parenthesis · an AI study companion