As I read your question, and think of the assignment, I'm looking at what's common. Meaning, they all deal with electromagnetic radiation. The differences are in the frequencies in the electromagnetic spectrum. Radio, Tv, or GPS, they function and provide benefits to us based on carrying information carried on the waves.
Moving electrons in a medium creates an electromagnetic field. Varying that current will vary the field. Modulating and controlling the current in a meaningful way makes it information.
I would start with the basic principle that each share, the electromagnetic spectrum, and the harnessing of the energy.
Radio, Tv, and GPS function with different frequency ranges, each having a particular behavior. Certain frequencies travel through some mediums and are effected by it. Others not. AM and FM frequencies behave differently, while microwaves drill past barriers that stop radio and tv cold. Some frequencies stay local (get absorbed and dissipate into the medium) while others literally bounce like a ball and carry on by virtue of reflection. Others still just penetrate and blow on by.
If you think about listening to AM versus FM, how far those signals go, why, and why you might like to use a highly energetic signal to carry location data reliably in straight lines (think of your trig classes), I believe you already have enough information to begin a pretty informative and well though out presentation. Good Luck.
