ADHD is a catchall that was designed by psychiatrists for a populaces that required a reason why for every behavior.
Every group of behaviors has other reasons BUT most are unpopular.
Most stem from lacks in home-life or diet that are not as easily corrected as just give johnny this medication and call it a day.
I have students with these symptoms who are medicated and they are useless when on the meds. I have other students who have the same symptoms but who are not medicated and I discuss diet with them or find out what stress they have at home that is raising their anxiety level. Most common is lack of attention which leads them to show off to gain attention.
Amazing how a few fruits and vegetables and a little positive attention (IE praise for a good job) can change these children. Also many times just having them on their feet being active does much good as it wears off the energy they otherwise would put to more annoying uses.
I contend that many teachers do not take into account the differing speeds at which children learn and fail to have enough to keep many children busy and then when they are done early they get noisy and boisterous which is normal kid behavior ... however they get labeled as hyper and having attention problems BC the busy work the teacher fills in with doesn't interest them so they act out.
I actually have a minor in Special Pops so I do have a fairly good basis for my theory