week 1

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=4&cad=rja&uact=8&ved=0CD4QtwIwAw&url=http%3A%2F%2Fwww.youtube.com%2Fwatch%3Fv%3DIvS3yA_TJ1Y&ei=giiwVOvcPIiGyQSM8YLgBg&usg=AFQjCNE07IPssUBesivkgiB9Pdkg1iUATQ&sig2=WJgGYORxeRyIpc86QEFjpw&bvm=bv.83339334,d.aWw