We went for Ben's 5 1/2 month check-up yesterday (our pediatrician is kinda hard to get in to, so you just go when you can...) He weighed in at 16 lbs (30th percentile) and was 27 3/4 inches long (which puts him in the 90th percentile.) His head also had a big growth spurt from his last appt, he was up from the 7th percentile to the 25th.
About 2 weeks ago he found his feet and he quickly figured out how to get them into his mouth.
He can even sit in the tripod position for a few seconds. You can feel his bottom two front teeth under the gums but nothing has popped through yet (thank goodness! I'm hoping he'll be a late teether!) He is also becoming a lot more interactive, particularly with his older brother. This isn't really new, but now you can just tell he wants to play or join in whatever Owen is doing so badly! He is also getting really grabby for anything he can get his hands on. He has pulled Owen's hair a few times, which usually ends up with Owen having a mini freak-out of "He's pulling my hair!!!" He grabs anything Owen hands him and quickly shoves it into his mouth. Owen is learning (slowly) not to give Ben things he doesn't want Ben to put into his mouth. I didn't realize this sibling rivalry business would start so early!