02 · The loop
There is no bank of questions anywhere. Each skill is a small program that writes a problem on the spot, along with its own worked solution and a list of the mistakes people usually make on that kind of problem, so you will never see the same numbers twice and there is nothing to memorize except the method.
You type and we read it as math rather than as text, so 2x+6 and 2(x+3) both pass, and 3/4, 0.75 and 6/8 are all understood to be the same number. When a skill is specifically about simplest form we tell you that an answer is right but not simplified yet, which is a different thing from being wrong. A small live preview under the box shows exactly how we read what you typed, so a missing bracket never costs you a problem, and on a phone there is a row of keys under the box for the minus sign, the fraction bar, the power sign and brackets.
If you miss once, we tell you the likely reason when we can see it in what you typed, something like "the minus sign belongs to the term after it" or "that is the product, and to divide you flip the second fraction," and then you try again. If you miss twice the answer appears with every step written out, including the why, and where it helps, another way to look at it.
Because every problem carries its own solution, a hint is just a slice of it. The first one is the rule, the next is what to do in words, then that step with the numbers filled in, and so on down the ladder, stopping before the answer. The first hint is free, and if you go further than that the problem counts as assisted, which is honest and nothing more than that.
Each skill has three levels, and in adaptive mode we watch how you are doing and aim to keep you right about 85% of the time, which is where the research says learning goes fastest. You can also set the level yourself, for any skill, with the minus and plus under a problem or on the Settings page, and nothing you set gets quietly undone.
Pick 5, 10, 25 or open-ended. The first problem is a warm-up and the last one is a little easier than the rest, so you usually finish on a pass. Mixed practice switches between skills on purpose, because deciding which method applies is the part people actually get wrong, and practice that mixes methods roughly doubles what you still remember a month later. If you leave a session half done the home page offers to pick it back up, and when you finish one you get a single true sentence about what you can now do.
Turn on the work area in Settings and every problem gets a scratch space under it, one step per line, rendered as math as you type and never graded. It is the margin of the paper.