For the past couple of months, Clara has been getting into four point position (hands and knees) with an apparent desire to be more mobile. Up to that point, her independent mobility had been limited to rolling with a little bit of squirming.
During her early experiments with four point, she would rock back and forth a bit before tiring and plopping on her belly. In March she started to try to move her legs forward, but would not move her arms in coordination. With one foot pulled forward under her bottom, the resulting shift in her center of gravity made it easy for her to transition to a sitting position. So, her method of mobility transitioned from rolling to roll, sit, flop, and repeat. Needless to say, this process is not a very efficient way to get to a desired toy.
Since March Clara relied heavily on the roll, sit, flop method of mobility, but would occasionally manage to sneak in one or two actual crawls before flopping on her belly. Each visit to the PT and OT began with the question "Is she crawling yet?". Within the last week Clara seems to have put all of the pieces of the puzzle together and is now putting several crawls together on a regular basis. Clara's OT and PT were very excited when she demonstrated her crawling prowess for them this morning.
For now, she needs to be motivated by something she desires that is out of her reach, such as any toy that Owen is using. Before we know it she'll be across the room in the blink of an eye. If she is anything like her brother, it won't be long before she is upright and cruising the furniture.