This was a little over a year and a half ago. I was at a high school marching band practice, and our instructor made us all stand at attention, holding our horns up and not moving or talking at all, for a very long time. During this time, our instructor was walking back and forth, yelling at us and making sure we were all in line. I wasn't a fan of this particular instructor, who only came once every few months or so, and my enthusiasm was low. Getting bored, I began to look around. At some point I became aware of what seemed to be a group of balloons, but at first I only caught glimpses as our instructor was being particularly harsh, singling out me and several others. When he turned his attention to someone else, I looked again to see, very clearly, that these were not balloons, but metallic discs. It was a large group of them - from what I can remember it looked to be anywhere from 20-30. It was very sunny, and the surfaces of these objects were silvery and reflective Furthermore, their motions didn't match the motion of the wind, like a group of balloons would, but rather resembled the motion of a flock of birds. They changed directions rapidly and constantly changed elevation, moving up and down in smooth motions. Eventually, I had to turn my attention back to my instructor and when I got the chance to look again they were gone. I would have taken a photo had I not been standing at attention for the entire duration of the sighting. I told my mother and she didn't believe me, but the next day I asked an acquaintance of mine, who was standing next to me when I saw it, if he had seen anything, and he told me that he had but that he had no idea of what it could have possibly been. I told my mother this, and she still seemed somewhat skeptical. However, about 2 days later, she was driving in a nearby area and saw something strange, and when she described it to me it matched what I had seen. We were confused and maybe a little bit uneasy about what it could have been, but we soon forgot about it, dismissing it as an unsolvable mystery. It still comes up occasionally in conversation, and, having recently become interested in UFO phenomena, I thought that I should report it.