Chalk trays do tend to be placed at an awkward height. Another argument for white boards, I suppose (except then there's always the danger of an indelible bright-colored streak across the back of any light-colored clothing if somebody leaves a cap off. Maybe chalk isn't so bad after all). Actually, that chalk board looks like a green board, which were pretty common when I was in elementary/high school (my combination easel/chalkboard had a black chalkboard, but my brother's, which was of a more "modern" design, had a green, even somewhat tealish, board). I wonder why? Were they supposed to be easier on the eyes than classic black, or something along those lines?
The semester one of my post-doc bosses sold my service back to the department half-time to make up a budget shortfall was at a place that had real slate chalk boards (like many science building at US universities the facility dated to right after Sputnik). Slate boards are a dream to use compared to those nasty green things—low glare, high contrast even with colored chalk, smooth feel when writing on them, erase well, and wash completely clean at the end of the day—but they are also fragile and expensive in comparison. And the more technology brings down the cost of the composites, the steeper the price difference compared to carefully cutting free, cleaving, mounting and transporting sheets of rock fercristsake.