When I worked with high schoolers I liked to introduce them to python. The documentation, IMO, is clearly written and easily understood by programming novices. It's got OO, imperative and (limited) functional paradigms available. Graphics are fairly straightforward, for example the built in turtle graphics library. With IDLE it has a good, free, crossplatform IDE that's simple enough to not overwhelm new programmers, but provides every feature you really need. The REPL lets new programmers quickly explore different parts of the language and their programs. And for sticking with primarily imperative code (here I mean that the programmer isn't designing new objects, though they may be making use of existing ones), the syntax is ludicrously straightforward once they get past the mandatory whitespace and spaces versus tabs.