“Your baby knows she’s the star of the show, and like all great divas, she’ll want your eyes on her at all times. She thrives on your attention. Don’t be surprised if she deliberately tries to get it by dropping things, banging objects, or even crying out when you turn away. She’s not acting up, just discovering the principles of cause and effect — when she calls, you jump!”
http://www.babycenter.com
Quoted from http://www.babycenter.com :
“Your baby may amaze you (and himself!) this week by rolling over from his back onto his front or vice versa. You can encourage this new behavior by placing him on his back and wiggling a toy on the side he customarily rolls to. Babies love positive feedback, so cheer him on and smile when he manages to flip”