Find the exact mistake you keep making.
Miss a question and Tachyon doesn’t shrug “weak at algebra.” It says: you read the y-intercept when the question wanted the x. Then it drills that one trap until it stops catching you. Reading, Writing, and Math. Every wrong multiple-choice answer in the bank is tagged with the reasoning behind it. Original questions, never recycled College Board material.
Everyone tells you WHAT you got wrong. Tachyon tells you HOW you think.
Most SAT tools stop at “you’re weak on Reading” or “review Algebra.” Tachyon goes two levels deeper. Every question is sorted into a specific sub-skill (45 in Reading and Writing, 104 in Math), and every answer moves that sub-skill along a mastery ladder, so your practice always climbs the weakest rung first. Inside each sub-skill, every wrong multiple-choice answer is tagged with the reason a student picks it: flipping cause and effect, reading the wrong intercept, going for the answer that’s true but off-topic. So a miss doesn’t just get marked red. The engine names the pattern it saw, deals questions built on the same trap, and steps in to teach: a trap lesson when the same mistake keeps recurring, a concept lesson when a whole sub-skill keeps resisting.
45 sub-skills in Reading & Writing, 104 in Math, each one leveled from developing to mastered.
Every wrong multiple-choice answer carries the reason behind it.
Watch it diagnose a miss.
A sample question, a wrong answer, and what the engine says back. Click around. Every choice is wired up.
A field study found that meadows cleared of an invasive beetle saw songbird numbers climb the following spring. Researchers noted the beetle strips the seed heads the birds feed on.
Which choice best states the conclusion the researchers draw?
Click any answer — every wrong one is tagged.
you flipped cause and effect. The birds came back because the beetle left, not the other way around.
Here are 3 items built to catch that cause-and-effect flip, and a 90-second lesson on how to read a causal claim.
Watching for the answer…
It steps in when you keep tripping the same wire.
The third time you fall for the same trap, the drill pauses for a 90-second lesson on it. Then it deals you fresh questions built on that same trap, so you can watch the fix hold. And when a whole sub-skill keeps resisting, it teaches the concept, not just the trap.
The loop.
Four steps, running every time you answer.
- 01
You practice.
Bluebook-style questions across Reading, Writing, and Math. MCQ and grid-in, numerically graded.
- 02
It names the mistake.
Miss one and it records which wrong choice you picked, and what that choice says about how you were reasoning.
- 03
It aims your next question.
Practice climbs your weakest sub-skill first. Inside it, the engine deals the questions built to catch your trap again and steps in with a short lesson when a pattern won’t break.
- 04
You watch it close.
Sub-skills level up from developing to mastered and beaten traps drop off the list, so your time goes to what you haven’t fixed yet instead of what you already know.
More questions isn’t the point. The right next 20 is.
A bank of ten thousand random questions doesn’t know which five traps keep costing you points. Tachyon does, and spends your time on those.
Original questions, never recycled
5,000+ original questions across Reading, Writing, and Math, difficulty-calibrated. We never serve real College Board questions.
Diagnosis at the grain of the wrong answer
Every wrong multiple-choice answer is tagged to a named mistake. That tag is what lets the engine name the habit behind a miss.
Full-length tests that mirror the real thing
Bluebook-style, module-adaptive practice tests: the truest score benchmark short of test day. Longer than a quick session, and worth it.
Reading, Writing, and Math. All of it.
Math is live: MCQ and grid-in, with the finest-grained tagging in the whole bank. No section is “coming soon.”
Everyone’s Pro for 7 days. Lock $19/mo before the timer runs out.
Right now every account has full Pro — unlimited adaptive practice and full-length, Bluebook-style tests, no card. Preorder the founder rate while the launch window is open and you keep all of it for $19/mo, for life, instead of the $29 public price. When the countdown hits zero, accounts without the founder rate move to the free tier (about 20 adaptive questions a day).
Preordering locks the price, not a surprise charge — you approve the card at checkout, and the founder rate stays $19/mo for as long as you keep it.
Founder
Preorder while early access lasts
- Everything in Pro, unlimited
- Locked at $19/mo for life — never the $29 rate
- Keeps your Pro when the 7-day window closes
- Full-length, Bluebook-style practice tests
- Cancel anytime
Pro
Standard rate after early access
- Unlimited adaptive practice (Reading, Writing & Math)
- Full-length, Bluebook-style practice tests
- No daily cap on drills or step-in lessons
- The public monthly rate once launch week ends
Free
Where accounts land after the window
- Your error report: named mistakes, by section
- ~20 adaptive questions a day
- Skill map, progress & step-in lessons
- Unlimited adaptive practice
- Full-length practice tests
Prices in USD. Cancel anytime; a subscription runs through the period already paid. The test-date pass covers one upcoming test date.
The same engine, pointed at your roster.
Tachyon grew out of a tutoring practice, and the tutor dashboard is built in: add a student by email, and once they accept, see their recurring mistakes by name and assign practice built around one specific trap, or a full timed practice test. We’re onboarding a small group of tutors and schools as design partners.
Roster, not spreadsheets
Every student’s sessions, mastery by sub-skill, and named recurring mistakes in one view.
Assign by trap
Build a set around any named mistake or sub-skill, or assign a full module-adaptive practice test.
See the why
Review a student’s wrong answers with the named mistake behind each pick, not just the score.
Watch your first trap close tonight.
15 minutes, no account. You walk away with an estimated score, a map of the skills to work on, and your mistakes named. Or start free and drill them now.