Check out 'Coding for Beginners Using Python' by Osborne.

Also have a look at 'Coding Projects in Python' by DK books.

Both these books are excellent and would enable a smart and determined 11 year old to learn to code.

To be honest these books teach coding in a way that is much easier than it was in your day. You can also jump on many, many websites and teach yourself how to code.

You're also an exception. Many, many kids read those old Osborne books and only a very tiny fraction like yourself became coders and an even smaller fraction became as successful as yourself.