This is a test to see if the wash down on your skein got rid of all the loose dye.*
You need what is left of your skein, some white cotton (no wash n wear finish) and a hot iron. Wet the skein and lay it on the white cotton and cover it with some more white cotton, then iron it- no stean- until the top piece of cotton is dry. Bring the cotton to class tomorrow.
* I prefer loose women to loose dye.