My UFO sighting (?)

ok, trying not to sound like a dork I am gunna finally talk about my only UFO experience.

It was a while ago, back when I was in my last year of high school. I was staring out of the window ( obviously not paying any attention to my maths class) just looking at the clouds, when I saw a small silver object in the sky. It was so far away I could tell exactely what shape it was but It looked rounded. At first I assumed it was some kind of plane or something but it just darted up into the sky only to reapear a few moments later. It would move slowly for a few moments then just dart of at incredible speed. I couldn't beleive the kind of manouvers it was making. It eventually just disapeared. The object was moving near a large radio mast of somekind in the distance. So I really don't know what it was and it was some distance away but I saw it making those incredible manouvers, moving thousands of feat in the air so quickly. Anyways thats my story.