Notes from the team building Locus: how the grader works, what we are shipping, and what we are learning about teaching math.
Locus has no multiple-choice math. Every numeric or symbolic answer is typed, and a computer algebra system decides whether it is right.
A missed problem should come back later, with the same skill and different numbers. What to bring back, when to bring it back, and why the correction is where the learning happens.
Locus gives every student a rating and every problem a rating, on the same scale. It is the Elo system from chess, pointed at a different kind of match.