I strongly suggest video games related material, in particular, Unity3D, Unreal 4, or for really simple intros, Scratch. All of these examples can be used to teach programming in a very interesting way that is fun for students and gives immediate feedback and results.
Unreal 4 is pretty amazing because the "blueprint" system is a visual block/node based programming langauge that can function as a complete programming language without much concern for codes/syntax.
Unity is better for direct coding. Boo is the easiest of the supported languages to teach, and very much like python, which is the 3D industry's standard scripting language, so I often start with that, and then some students move on up to C# coding. It's really about the same but with slightly different syntax, and of course the C# is less forgiving.
Another great method, although it isn't quite a full blown game engine, is Python programming in Blender. There's an interactive command line for working with the 3D scene. The great things about programming for 3D software and game engines is that stuff can be extremely immediate and visual, so concepts can be understood quickly. For games, often you can see what's happening in your "world" by pausing the game and interactively exploring the state of things. Blender actually has a built in game engine, although it's pretty basic and limited compared to Unity or Unreal 4.
If they are young, then you needn't focus on job skills just yet. What's more important is getting them interested so they start teaching themselves and getting into the habit of independent learning. You also don't necessarily *need* to do anything with hardware, focusing on software can work just fine as a intro for students.
In conclusion, I suggest that you should be successful using anything that gives very immediate visual feedback on the state of the world (without debugging or printing/logging), and which has the "oh wow, this is fun" factor, something that grabs children's attention and triggers their imaginations.
I can say with confidence that when teaching children, grabbing their attention and making it "fun" is a huge priority. I've been teaching this stuff for almost 20 years, and the games / VFX industry is full of my students. I've taught many adults, but also many children as well. If I can help at all, or if you would ever like to talk, feel free to contact me more directly. If you like, you can email me using: questions in the domain teaching3d.com (To avoid spam I didn't directly put the exact info there, but you can piece it together I'm sure!)