This is a cute little side story set during the climactic final scenes of the main Elantris storyline. Basically, it’s a story that Sanderson had originally in mind for Elantris but cut due to pacing or other issues.
Basically, it follows Matisse, an Elantrian who is charged with watching after the children and ends up saving them all with the help of Ashe the Seon.
It’s actually got a cute postscript about where the where the name Matisse came from.
Worth the quick read.