I have been trying to convince local participants in the Let's Talk Science program that I can connect almost any of their course material to computer science. I would like more teachers to request computer science activities through the program. It's not an easy task, because the assumption is that only computer science classes would benefit from computer science activities.
Yesterday, I did an activity for a grade ten science class that recently finished their physics unit on optics. (I only had half a class this time, but could have easily spent an entire class on the activity by adding some more hands on stuff.) I started things off by discussing the difference between a bitmap and a vector graphic. Once the students understood this, I asked them what they thought 3D graphics would be made with, and they guessed vector.
We talked a bit about how objects would be described mathematically in 3D space, and how you could wrap a bitmap around vector-based objects to texture them. We looked at how to take a 3D object and represent it as a 2D object by making shadows onto the projector's screen. I explained that this was called projection. I quickly reviewed the geometry rules they had learned for lenses, and showed how it worked for an even simpler case: the pinhole camera.
I told them how film cameras worked (only a few even remembered having one!). I asked them what they thought was different for digital cameras. What was the equivalent of the film? They guessed the screen, the memory card, and so on, but didn't guess that there was a sensor that acted like film.
After discussing the sensor, we did the CS Unplugged activity on image representation to get a feel for how computers can store image information.
And just like that, I got to teach them computer science in the disguise of learning physics. Hurrah! :D
When I do get the opportunity to do computer science activities (either for Let's Talk Science or other outreach), I generally find that the students have a real sense of accomplishment after they (inevitably) grasp the concepts. Add that to the overall benefit of understanding even a bit about how computers - such an integral part of our lives today - work, and I think you have a compelling reason to invite a computer scientist to any high school classroom.
If you're interested in how you might be able to connect computer science activities to other high school subject areas, check out this document I put together a few years ago for ideas.