From the sound of your requirement and your level of experience I think Mark's suggestion of a morphing app is totally suitable. And Keep It Simple Stupid applies. I'd do it with stills (remember, while the morph section is showing, your audience aren't going to looking at whether the background is moving or not)
So we have....
Video of child arriving in frame in gear
Snaphot of the very END of this clip
(morphing vid to be created)
Snaphot from the very beginning of the next clip which is....
The vehicle (Sitting there, but could then drive off)

I suggest video before and after as this will look more impressive than just stills before and after.

Software - for starters look at WinMorph from debugmode. It's FREE and the video tutorials are great to get you going.

Let us know how you get on. (And a great idea BTW, it's given me some inspiration for my next feature starring my 3yo daughter)

__________________
Tim