Instructors need to be very creative. Most of our classes are outdoors, away from slide projectors, lap tops, etc. If you have a bit more time and access to indoor facilities, by all means take advantage of your good fortune and prepare a decent Powerpoint presentation and certainly handouts.
Even if your class is taught completely outdoors, I strongly recommend preparing handouts of some sort. I maintain my training material on a website. Others provide a sheet or two for key topics. The SWR classes cover a wide assortment of material - far too much for many students to retain completely in one sitting. You should also recommend a decent book or two - they are inexpensive and enable students to continue learning after the class.
Prepared presentations are for more complex topics. Mechanical advantage is a great example "some assembly is required". To save valuable class time, you can have a helper set-up several demonstrations while continuing to teach another topic like knots. Props are exceptionally valuable in prepared presentations. I love demonstrating a vertical pin in a standard hole cockpit by lifting the rear of a kayak to a high angle and having them attempt to escape. I often lay out a large variety of gear on a tarp to show examples of thermal protection choices and various rescue gear.
As instructors, you are expected to be conversant on all of the SWR curriculum - think pop quiz. SWR students will be asking lots of questions during your classes and you need to be prepared to provide explanations quickly and efficiently. During knots training, you should be able to demonstrate any one of the basic rescue knots and provide an example where that knot can be used effectively. Impromptu presentations are expected to be short in duration - just a few key highlights. Good short presentations take advantage of their surroundings like tossing a small stick into a hole to demonstrate recirculation.
There are lots of excellent articles on the web for presentation tips & techniques. Toastmasters, International is a great organization devoted to public speaking. Everyone has a different style but there are a few key ingredients for effective presentations:
- Be prepared
- Keep it short
- Engage your audience
- Address the audience needs
Here is a really good article on killer presentations: 18 Tips for Killer Presentations.