There are now ten quizzes on the site, covering the arithmetic methods and four science topics. They ask one question at a time, tell you immediately whether you were right, and explain why. Nothing is recorded anywhere except in your own browser.
The arithmetic questions are generated
Not typed. A small program picks the numbers, works out the answer, and builds the question around it. That has one large advantage: the correct answer cannot be a typing mistake, because nobody typed it.
The wrong options are the interesting part
Most multiple-choice questions surround the right answer with numbers that are merely nearby. Ours are built from the mistakes the method pages already document.
- One option is the answer you get if you drop the minus sign on a negative partial difference.
- One is the answer you get if you subtract digits instead of place values, taking the smaller from the larger in every column.
- One is the answer you get if you leave out a partial product, usually the tens times ones one.
So the option a student picks says something. Choosing the dropped-minus-sign number is not bad luck, it is a diagnosis, and the explanation names it.
Why there is no sign-in
Because the audience is children, and the safest place to keep a score is somewhere we never see it. Scores live in the browser's own storage, they are visible to nobody else, they are never sent anywhere, and there is a button on the quiz index that erases them. A student who wants to be wrong eight times in private can be.