When my son was in standard one, he's crazy about dinosaurs and was fascinated with Egyptian myth & history (he had quite a few books on that). He said he wanted to be an Archaeologist (that's a big word...and a big ambition for a 7 year old!)
When he's a few years older, I bought him a lot of science books & he fell in love with marine plants and animals (he could name so many sea creatures that I've never heard before). He changed his ambition and said he wanted to be a Marine Biologist. (another big dream, he must had read it from one of the books)
Ever since he started playing with BB Gun 2 years ago, he became a bit obsessed with guns. He would search and read all types of reports on guns and he even had a thick encyclopedia on that (I bought him one). He then declared he wanted to be a Weapon Specialist. Sounds big but dangerous and surely not a profession I'd ever approved! Yesterday he said actually he wanted to be a "Gunsmith" and not a "weapon specialist". (I didn't bother to ask him the difference between that 2 professions)
Oh yes, some time ago he also did mention that he wanted to be a Professional Gamer ...after he started playing X-box last year.
My son is the type of boy who'd read in details those topics that interest him (Once he's obsessed with Robotic & Astronomy too). That's his strength and I encourage to him read & explore (his command of English is getting stronger). I just wish that one day when he's well equipped with all kinds of knowledge, he will go back to basic to differentiate between Good & Bad, and to choose a noble job that can help mankind.