How kaoshen.co works: building around the miss, not the question

Most SAT practice tools are question delivery systems. You answer, you see whether you were right, you read an explanation, you move to the next one. The question is the unit of work, and once you have answered it, it is finished with. kaoshen.co is built the other way around: the question is disposable and the mistake is the thing worth keeping.

That difference shows up everywhere in the product, so it is worth walking through what actually happens from the moment you get one wrong.

Step 1 — you practice a skill, not a topic

The question bank is organized by the College Board's own taxonomy: two sections, eight domains, twenty-nine skills. That is the same structure the real test is assembled from, which matters for a practical reason. "I am bad at math" is not something you can act on. "I lose points on systems of two linear equations in two variables" is a Saturday afternoon of work.

Every skill has its own page, showing how many questions are actually in it right now — a live count, not a rounded marketing figure, and a skill with nothing in it yet says so instead of pretending. You do not need an account to use any of it, and there is nothing to pay: the questions, the hints, and the explanations are all free.

Step 2 — each question carries the reasoning, not just the answer

Every question ships with four things beyond the answer key:

• A strategy tip — one sentence naming what the question is really testing, which is often not what it appears to be about.
• Three hints, which you take one at a time. Taking a hint is not cheating; it is a cheaper way to find out which step you were missing than staring at a blank page.
• A step-by-step solution, shown after you commit to an answer.
• A reason each wrong option is wrong — usually more useful than the correct method, because the wrong option you picked is the one that matches how you were thinking.

Step 3 — the miss is logged for you

When you get one wrong, which option you picked is recorded — not just that you missed a percentages question, but which of the four wrong routes you took. That is the raw material the rest of this depends on, and it is captured without you doing anything.

There is nothing for you to do here. No screenshotting, no error journal, no tagging. This matters more than it sounds like it should. Every teacher recommends keeping an error log and almost no student sustains one, because the moment you get a question wrong is exactly the moment you least want to stop and write about it. A log that depends on your discipline at your least disciplined moment is a log that will be empty by week three.

Immediately, what you get back is the reason your specific option was wrong. That is the part most tools skip, and it is the part that tells you what to change.

What comes next: proving you fixed it

Re-reading the explanation of a question you have already seen mostly tests whether you remember the explanation. So instead of showing you the same question again, the engine generates a fresh one built around the same misconception, with your exact error planted as one of the four options.

If the trap still catches you, nothing has been fixed, and now you know that while it is still cheap to find out. Getting the new one right is the only thing that counts as fixed.

And it comes back on the forgetting curve

Beat it today and the same misconception is scheduled to return three days later. Clear that one and it is scheduled again a fortnight after that. Miss either and it comes back tomorrow instead. The intervals are not arbitrary: they sit roughly where recall for a freshly learned correction starts to fall off, so the retest arrives just as the memory is getting shaky, which is when testing it does the most good.

You can try three question-bank problems before signing in. Google sign-in is what makes the rest possible: your record follows you across devices, the spaced retests can reach you by email, and the retest itself requires a signed-in account, because there has to be somewhere durable to keep the schedule.

Where the questions come from

They are written and machine-checked by us. Every Math question has to be solved twice, independently, with the options withheld on the second pass so the two derivations cannot both anchor to the same option list; a computer algebra system then evaluates both results and the stated answer and requires all three to agree numerically. Each wrong option must also come with an expression that reproduces exactly that option — a distractor nobody can explain does not ship. Questions that fail any of those gates never reach you.

We do not copy questions from other prep companies, and we do not reproduce material we are not entitled to publish. Where a question is an officially released College Board item, it is labelled as one.