If this principal, or any principal for that matter, can't understand that, developmentally, kids need "free time" during the day, then he/she certainly does not need to be in an administrative role. Must adults can't sit all day and work without a break of some sort. Why should we place those limitations on our students? The children in my classroom and throughout our school have always been successful on "THE TEST" and I attribute that to the fact that we do not drill, drill, drill all the time and they have freedom within the classroom. We take two breaks each day. The kids are allowed to keep food/water at their desks throughout the day. Brain research shows that kids need these things throughout the day in order to be successful. If your principal is, indeed, upset with the fact that your kids were taking a "brain break", pull up some of the latest research and show him/her.