In my work in the field of dance and kinesiology (study of movement), I recommend my students to sit in chairs as little as possible.  Teachers and Parents: if your child is having difficulty sitting in a chair for the entire study period or simply does not want to do so, please consider these kinesethic reasons why.
Sitting puts more pressure of gravity on the spine that any other position. When you are standing you can use your legs and abdominal muscles to lift upward against gravity. When you are laying down the gravity presses across the entire body, and the spine is relieved.  But when you are sitting the gravity is pressing mainly on the top of your head and shoulders.  When you consider that your head weighs about 10 pounds and it is balancing on the top of your spine against the constant pressure of gravity which is 14 pounds per square inch, you can envision the pressure put on your spine, a mere balance of vertebrate and skeletal core.
In a classroom, I believe it is best for students to accomplish most activities while standing. Reading, working on the computer and most importantly, working with the Teacher and other students, can be accomplished while standing.
Students should also have a place to rest comfortably, such as a mat where the student can lay and stretch. Sitting in a chair requires use of leg and back muscles and should be in correct posture without the neck bent toward the desk. Students should be allowed to rest from this position. Sitting is best if it is only 15 minutes at a time (such as during a lecture or film segment). Ideally, when working  seated, the student can use an easel set to the correct height to allow the neck to rest comfortably on top of the spine.
For some students this will help them to be less agitated during class.  For others it will benefit health in terms of weight loss and increasing core strength. Student should also be advised by the Teacher on correct posture to enhance brain health.
Tara Pelton, B.A. is a graduate student at Northridge University in the field of special education. She is also a tutor. She works in Los Angeles.