I wouldn't worry too much about the kids being intimidated or bored. As for intimidation, kids of any age will surprise you with what they can do, and as for bo

I wouldn't worry too much about the kids being intimidated or bored. As for intimidation, kids of any age will surprise you with what they can do, and as for boredom, if this is an after-school program hopefully the attendees will be self-selected to be interested in the subject. Just keep providing them interesting, achievable projects, and be very encouraging and enabling. I can't speak to curriculum, but could you set up each student/team of students with a Wordpress install, and have them build a website for whatever interests them? Start with basic working with software and following instructions, go into configuration and customization, eventually have them write plugins to do basic web-app-like things?