Apologies in advance if you already know the following but you may like to consider it anyway:
Your primary document to begin lesson planning should be the appropriate authority’s/FTO’s ground school syllabus - teach the syllabus and not a particular textbook.
I am unaware of any PowerPoint presentations or supplementary material associated with Trevor Thoms products. You may have to create a lesson plan and then create your own PowerPoint presentation scanning and inserting appropriate diagrams from relevant texts etc. It makes sense that the students see in lectures what they will be reading and studying but I will leave the copyright issue up to you.
There is some excellent information available from the FAA website
Handbooks & Manuals which is easily transferred to a PowerPoint presentation.
Having created your PowerPoint presentations your printer selections should include options for handouts, note pages and outline views. Although I believe in handouts and note taking during lectures in principle, be careful that your students don’t spend too much time writing when they should be listening and contributing to class discussion.
For audio visual aids I know that You tube has a lot of useful aviation type presentations but I strongly recommend that you consider their relevance to the syllabus. You are to educate and inform rather that entertain. Jeppesen has some DVDs available which support their products but could be used to supplement or reinforce the more basic generic knowledge, principles of flight, weather, technical etc. Each topic is around 10 minutes in duration so they can be usefully inserted into a period of instruction. There are some useful online ASF courses sourced via the AOPA website
AOPA Online: Aircraft Owners and Pilots Association which could be used for student review. Once again, ensure what you recommend fits your syllabus.
Take some field trips out to a local airfield where there is much too see and discuss. Have the student create a “what to see and discuss list” so your trip can be guided and planned within limits.
Welcome to the ground school instructor club, I hope you enjoy the work.