I think I was told to go fly a kite!
I'm not a teacher and I won't go through a long explanation... Just to say, that a picture is worth a thousands words.
<iframe width="420" height="315" src="http://www.youtube.com/embed/nCm2UCj6eDU" frameborder="0" allowfullscreen></iframe>
http://youtu.be/nCm2UCj6eDU