I'm working with middle schoolers for the First Lego League competition. The ones with some programming experience either had a Mindstorms kit at home or were playing with mods for games. But a number of the students seem inclined towards programming, but overwhelmed by how to get started.
There's some advantage to a stupid simple DOS computer with a copy of some BASIC implementation and every math textbook from grade 3 on having BASIC programs at the end of every chapter or section.
I was actually working on a longer comment that would've included a mention of scratch. Right now the focus is on the robotics competition, but in the spring that may be something I try to introduce them to. The problem will be access to computers. There just aren't enough available for the entire group (though attendance has dropped recently, so unfortunately there may be enough computers to handle all of them soon).
If it helps, chromebooks are nice little laptops that can be had for a couple hundred bucks. If you have monitors and keyboards a Raspberry Pi might work well as a computer and is about $50 with SD card, power supply, etc.
There's some advantage to a stupid simple DOS computer with a copy of some BASIC implementation and every math textbook from grade 3 on having BASIC programs at the end of every chapter or section.