Programming language for teenagers
I highly recommend checking out a language called Processing. Processing is designed for novices, and makes it easy to create visual and interactive programs without a ton of boilerplate.

Here's an example Processing sketch:

void draw() {
  ellipse(mouseX, mouseY, 25, 25);
}


This is a full program that draws a circle wherever the mouse is, 60 times per second.



Related:


Using Processing as an entry point in an Introductory Course
Programming languages specifically designed for beginners
The order of subjects in beginner's curriculum
Order to Teach Topics in an Intro Programming Class
Make it easier, and quicker to get to the start


Shameless self-promotion: I wrote a series of tutorials for Processing available here. I'd love to talk more about using these in a curriculum.