I’ve always got an eye out for old art school color charts and the like, and find this quite a satisfying one. The watercolored rounds representing progressively diminished color intensities are paper cutouts, pasted down in a lightly pencil drawn grid. Along the right edge are a couple of comments, written in pencil—at least one of them by EW Hall him or herself, who initials the comment, noting “too much black, not enough blue.” Looks like Hall received a “B” on the assignment, marked at lower right!
11” x 14”, done on heavyweight sketchbook paper. A bit of toning around the edges of the paper, and some glue (rubber cement I think) showing around the edges of some of the rounds. C. 1920-40s I would guess.