He's got the position down.
He's even gotten the hang of how his arms should move, now. He lifts first one, and then the other, pulling himself a little forward as he goes.
It's the legs that get him, every time. He's finally realized that trying to straighten them out is not the way to go. However, it hasn't quite clicked in his brain yet that he must move one knee forward at a time. His constant attempts to shuffle both of them forward at once cause him to lose his hold on the starting position, knocking pelvis to the floor and leaving him fruitlessly flailing in one place.
At which point, if he hasn't completely run out of patience, he starts the process all over again.
It fascinates me that he hasn't given up on the whole thing and started dragging himself around the room in an army/inchworm crawl, like his sister did initially. No, he seems determined to do it properly, and will not rest until he's figured the whole thing out.
In the meantime, he can get around pretty well when he really tries to, by rocking back and forth as he sits upright- which scoots him slowly forward as he starts to gain momentum- or by pushing himself backwards out of the upright crawling pose. I've seen him move across an entire room this way.
He's also learned, through the process of trial-and-error involved in figuring out how to crawl, how to push himself back up into a sitting position from his tummy. This is a skill that will no doubt prove helpful to him, having a big sister intent on knocking him down, just for the fun of it, several times a day. (Her parents' attempts to stop this annoying and nonsensical behavior have proved unsuccessful, but thankfully, Michael takes it all like a pro.) Although he usually ends up on his back when this happens, I have seen him roll from back-to-belly twice in the last month, so I know that he finally figured that move out (though I'm not sure exactly when). What I have not yet seen is Michael putting it all together: first rolling from back-to-belly, then pushing back up to sitting position. He's usually pretty happy lying lazily on his back for awhile until I swoop in to "save the day" and set him back up with his toys again. Making a mental note: I should probably stop doing that...
He'll be eight months tomorrow, and as much as I am enjoying the time I still have left with only one "baby" that has nearly unlimited access to T-R-O-U-B-L-E, I am rooting for my little Michael to master this new crawling skill just as soon as he can.
He's a hard little worker; he's certainly earned it.