sketch pad for laptop

I have volunteered to start teaching a 6 hour portion of our state association's review class for the surveying exam.

I was at the Kentucky Conference earlier this year, and one of the instructors, Mr. Horton I believe, had a sketch pad that was connected to his laptop. It allowed him to do sketches that showed up on the projector.

I cannot find my bookmark where I had found it before. Does anyone know of anything similar? I will be teaching the basic survey math, horizontal and vertical curves, and another portion that escapes me at the moment.

I am starting my search tonight, but thought I would ask my friends here if they have used anything like it.

Thanks!

Jimmy