How the engine works.

Most tools track one thing: right or wrong, maybe by broad topic. Tachyon tracks two.

First, the sub-skill. “Transitions” is too coarse a bucket, so the engine tracks contrast transitions separately from cause-and-effect ones, and “linear functions” splits all the way down to reading a linear graph. There are 45 of these in Reading and Writing and 104 in Math, and each one you practice carries a level: developing, proficient, mastered. That axis is the spine. It decides what you practice next, weakest first.

Second, the named mistake. Every wrong multiple-choice answer in the bank is labeled with the specific reason a student picks it. That axis is the lens inside each sub-skill. It decides which misconception to fix.

In Reading and Writing, a wrong choice might be a flipped cause and effect, an off-topic-but-true answer, or the right idea pushed past what the text supports.

In Math, it might be reading the y-intercept when the question wanted the x, a slip in the slope arithmetic, or solving for the wrong variable. Math is tagged even more finely than Reading and Writing, with over a hundred named mistakes in all.

The bank is original and difficulty-calibrated, and every one of those tags is built in when the question is written, so a miss can be named the instant it happens.

One miss is noise; a pattern is worth stopping for. When the same named mistake shows up a third time, the engine pauses the drill for a 90-second lesson on exactly the trap you keep falling for.

And a struggling student doesn’t always repeat one tidy trap; sometimes a whole sub-skill keeps resisting. When that happens, the engine steps in with a concept lesson instead: the core idea, the standard setup, a worked example.

Then it hands you fresh questions on the same ground to confirm the fix held. Like a tutor leaning over your shoulder, except it’s 2am and it never gets bored.

As a sub-skill levels up and its traps stop catching you, its questions show up less and the next weakness moves to the front. You’re always spending your limited time on what you haven’t fixed yet.

That’s the whole idea: practice aimed at where you’re actually losing points, re-aimed after every answer.