I sometimes visit classrooms to make suggestions about managing a hyperactive student. A 3rd grade teacher in a local Catholic School used a technique that ought to be used more often for ADHD children during group drills.
Jill asked the entire class to write answers to oral math problems. However, she had them write on black slate, not paper, and each held their slate overhead when done. This method allowed her to sort which students performed the tasks. The quicker ones were then split off to a side-task while she gave extra help to the erratic performers.
The slate is potentially a clever gift to ADHD students who frequently have trouble waiting during class drills. The teacher may ask a question, the student writes his answer and has nothing to do, especially with his hands, while the rest of the class writes and looks up when done with the problem. During such waits, ADHD kids often find a string, a pencil, or an eraser to roll on their desk. Unfortunately, the eraser is more immediate and interesting than the teacher; they don't switch back on to her when she announces the next problem. Put such students in a barren room and they will play with belly lint during these waits. The problem is not one of distraction, but perhaps one of seeking distractions.
Raising the slate occupies two hands, almost forces him to raise his head and face forward, and perhaps encourages him to check his latency against other children. An ADHD child can be reinforced more quickly by a smile or a direction to help another child. The extra motor activity might even help him maintain arousal in a manner possibly similar to that of fidgeting.
Sidney Zentall, author of several texts on educational methods, claims to have ADHD; I believe her. Dr. Zentall once described similar compensations to the slate but in her home office. She . She reports having four desks at home and rotates her use of them during her day. The change in scenery cuts into her satiation. She has one desk elevated to let her work standing up. I've tried such a desk; it helps me and, anecdotally, it has helped some of my clients.
In a like manner, I have some male clients who claim to have little reading retention but have gone up to 12 minutes of concentration time, with computer manuals and without stimulants, by walking while they read. I once knocked off 4 chapters of Wright while on my NordiTrak.
It ought to be worth a thesis somewhere to verify these things.
The tie of all this to sociobiology and evolutionary psychology? Motor inhibition is a fundamental weakness with ADHD. The kids fidget, move to excess, and act prematurely with their mouths as well as with their arms and feet. More recently, the Executive Functions have been linked to ADHD in that hyperactive (non-manic!) children are more likely to have weaknesses with the Executive Functions of planning, persistence, imagination, word retrieval, memory formation, and timing, especially of delayed responses. These same EFs would have given substantial advantage to people who used them as part of hunting or of warfare. The ability to persevere and to wait, to imagine the likely track of quarry or a foe, and to communicate those imaginings perhaps arose as a refinement of pursuit and attack sequences. Thus, moving in order to concentrate makes sense.