The time has finally arrived when you look forward to the changes your baby undergoes. At this period of time, rolling both ways is the obvious physical development milestone. The fun part here is developing this particular milestone. Try putting toys beyond his or her reach as that would prompt him that rolling would be the way to reach for it. As a note, usually they roll first from front to back however when the opposite happens, it still considered as normal.
Another is development of full color vision. This is pretty easy as what you only do in response to it is show her colourful pictures giving her a very fun experiences as she or her can truly appreciate the colors already.
At the cognitive aspect, saying names is being tolerated here already as he or she can already respond to her name in this period of time. Try introducing other family members one at a time as well.
But the most exciting one is object permanence, the act of hiding something and she goes look for it. In the deeper sense, they learn the existence of objects even without their site. The best play for this is “peek-a-boo”.