Your post title and what you're asking are two different things. Kicks, trim, fins and the like are one part of the topic, and I agree with everyone who said spend the time in the pool instead of having your students enjoy a slow, agonizing death by PowerPoint. There are some buoyancy related topics that do lend themselves to PowerPoint and would make great handouts. If you figure buoyancy is a function of weighting and air spaces, then there are several topics you could cover with PowerPoint. Buoyancy characteristics of various tanks (aluminum, low and high pressure steel, low vs. high volume tanks, etc) is a biggie. Over the weekend, a friend called me to ask what the buoyancy difference is between a full and empty 80 cu ft tank, and this is coming from someone who has been diving over 30 years. Other topics are buoyancy differences between no, thin, and thick wetsuits, and drysuits with various undergarments. Plus buoyancy differences between backplate/wing setups vs. traditional BCs. And all the places are gets trapped that affects your buoyancy. Then go through how to come up with a starting point for proper weighting in different situations, e.g., diving in Vancouver Island in a drysuit vs. diving on vacation somewhere warm and tropical. Finally, maybe a graphic showing how much air will be in your wing or BC if someone is correctly weighted vs. grossly over or under weighted, and how depth affects air inside a wing. Plus maybe another graphic or a few words explaining why you want to end up with no air in your BC when you're at the end of the dive hovering at 15 ft with 500 psi left in your tank for your safety stop, and how you can use your breathing to easily control your buoyancy at that point in the dive. This would make a nice handout for your students to take away and you can go over all the other things you listed in the pool. If your students can't get properly weighted to being with, or close, they're going to be struggling with kicks and trim the whole time in the pool