Allow them time to figure it out: help move their interest level from a 5 to a 6, not from a 1 to a 10.

These kids are in middle school. Their interests are still developing and will change rapidly. Their long-term thinking (frontal lobes) haven't yet developed to the point where they can logically think through the long term implications of their choices. This occurs sometime in the late teens to early 20's. If you start with technical descriptions, you lose them - FAST. Instead, focus on what they can see, touch, & feel today. That will put something in their memory banks they can pull out later.

If I were to give a short 10 minute talk to 6/7/8 graders, I would show them - on my computer - a demonstration of a mod being made to Minecraft or something else they are familiar with. I would do this at a very high-level.

Overall take away:
   - Show something, don't tell it
   - Do it from a 30,000 foot level
   - Do it quickly (KISS - keep it simple. stupid)