Getting bigger is significant for DS3.5 too! He has a long list of things he's waiting to do. E.g. I don't have to hold your hand because I'm a Big kid; I'm going to kindergarten! but first pre k then high school and then college (where he will of course have his own television and be able to watch super heroes whenever he wants); when I'm 16 I will drive in the car and you can be the passenger; I'm going to be an astronaut and you can come for a ride in my rocket, Falcon Heavy! ... on and on. I think he's planned his birthday party several times already this year, and isn't shy to assert "his plans" for upcoming weekends. Admitting I've allowed too much multimedia recently due to exhaustion at night.. he's totally into Next Gen Star Trek, Warehouse 13, and Doctor Who. He's also into science exploration (finding bugs, learning about weather, doing basic experiments - making snow this week was a blast). Otherwise running and climbing and lots of Frisbee.
Did I mention testing authority. That's definitely a passion right now (smile and sigh). He actually tour guided for his class on a recent field trip to a local museum we'd been to once before (when he wasn't trying to elope from the group to explore his own agenda). The teacher said he knew where all the maps were and was showing the exhibits. Again, the I'm going to be a big kid (and part of me is right now but not in 5 minutes thing). So much ownership of experience, and looking forward either out of frustration for being held back because he has knowledge of safety skills (don't run in the parking lot, rattles off telephone and address in case he gets lost) but demonstrates safety skills like a 3 year old, and for enthusiasm moving ahead towards the new and awesome.