If BASIC is the kind of language you want to teach him then VisualBasic .net would be a better option. However, this limits him to MS Windows platforms for the most part. The problem with BASIC is that it has no set, updated, standard for it. Which is why programming languages with vast differences like REALBASIC, PowerBasic PureBasic and FreeBASIC exist (all great btw - although I'm a PureBASIC fan!)
I recommend Python though, it's shares a lot of similarities to BASIC, is standards compliant and you (as the initial teacher) shouldn't have too much issue picking it up, reading it's code and explaining it.
if you're choosing Qbasic because that's the only language you know best. Then there's always QB64 although I personally recommend Python. (I'd link you but right now browsing via a tiny Craptop thing).