Of course it is the "Keep hands OFF this Book" written by a GR in blue crayon on the inside front cover of this old German language school book that sold me on it, but then it was a delight to discover a few small drawings and crayon coloring on some of the geometric shapes scattered across its pages. And the printed matter itself is quite lovely, combining bits of arithmetic and geometry and penmanship and German language on each page. Some pages at the front are long since missing, but there are still a good 50 pages or so left. I've photographed most that feature interventions and a few others too. 

7 5/16” x 5 1/8” x 5/16” . Very well worn as documented, but still holding together and pages themselves are in pretty good shape.