Find the exact mistake you keep making.
Every wrong answer in Tachyon’s bank is tagged with the mistake behind it. So when you miss a question, it doesn’t say “weak at algebra.” It says you read the y-intercept when the question wanted the x — and then it drills that until it stops happening. Reading, Writing, and Math. Original questions, checked by hand.
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 went two levels deeper. Every question is sorted into a specific sub-skill (44 in Reading and Writing, over a hundred in Math), and every wrong answer choice 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 tells you the pattern it saw, pulls up questions built on that same trap, and if you fall for it a third time, it pauses and teaches it.
44 in Reading & Writing, 100+ in Math.
Every wrong MCQ choice carries a named flaw.
Watch it diagnose.
A real 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 REVERSAL, and a 90-second lesson on cause-and-effect claims.
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 and you get a 90-second lesson on it. Then it deals you fresh questions built on that trap, to check the fix held.
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 logs the mistake.
Miss one and it records which wrong choice you picked, and what that choice says about how you were reasoning.
- 03
It drills that exact flaw.
It sends you the questions built to catch that trap again, and steps in with a short lesson when you keep repeating it.
- 04
Your plan shifts.
As a weakness closes, the mix moves on. You spend your time on what you haven’t fixed yet, not 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 only shows you those.
Original, hand-checked bank
5,300+ questions written and verified by us, difficulty-calibrated. We never serve real College Board questions — everything is original and generated-only.
Diagnosis at the grain of the wrong answer
Every wrong MCQ choice is tagged to a named mistake. That tag is what lets the engine name the habit behind a miss.
A practice surface that matches the real test
Module-adaptive, Bluebook-style. What you see here is what you’ll see on test day, minus the surprises.
Reading, Writing, and Math — all of it
Math is live: MCQ and grid-in, with the deepest tagging in the whole bank. No section is “coming soon.”
Free is a real tool, not a trailer.
The full diagnostic and your error report cost nothing and need no card. Pro removes the ceiling.
Early access: every new account gets the full Pro feature set free right now. Pricing kicks in later — early users keep a discount.
Free
- Full diagnostic
- Your error report — named mistakes, by section
- ~20 adaptive questions a day
- Reading, Writing & Math
- Unlimited adaptive practice
- Step-in micro-lessons
- Full recurring-mistakes dashboard
- Full-length practice tests
Pro
- Everything in Free
- Unlimited adaptive practice (RW + Math)
- All step-in micro-lessons
- Full mastery + recurring-mistakes dashboard
- Full-length practice tests
- Study plan that tracks your test date
Prices in USD. The test-date pass covers you through one test date.
The same engine, pointed at your roster.
Tachyon started as the practice engine behind a tutoring practice. The tutor dashboard is built in: add students by email, see every student's recurring mistakes by name, and assign practice built around one specific trap — "10 questions where the trap is OUT_OF_SCOPE" — 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 from any error tag or sub-skill, or assign a full module-adaptive practice test.
See the why
Review a student's wrong answers with the tagged reasoning behind each pick — not just the score.