I agree that the first lesson should be about the basics, and should include a basic simple soap. Then if you want, you can do an advanced or maybe an 'introduction to swirls' lesson the following month (and have them bring back at least one bar of their first soap so you can see how they turned out after a 4-week cure and talk more about cure time.) During the second lesson, you can go into more detail about colors, fragrances, even additives and do a simple swirled soap. Or an 'introduction to colorants & fragrances in soap' or whatever.
Paprika oil that you have made ahead of time would make a lovely color. Make sure you show them how to strain out the actual spice so they don't end up with bits that might irritate mucous membranes (tender lady parts). Of course that depends on if you use sweet or mild paprika to make your oil (re: capsaicin content.)
I would avoid anything that will create a longer cure time, so keep your OO percentage low, and also not a salt bar. Your student(s) will not want to wait long for the cure of their very first soap.
Adding a fragrance of some type would be nice, if the student so desires, so maybe offer two or three options from your stash, but let them know fragrance is optional. Same for colorants; offer 2 or 3 options and maybe provide a handout with url's to look up info on natural colorants if they want to make soap at home from their pantry.
For natural colorants, maybe buy a small baby food container of puréed carrots, or purée some you have on hand. Others to suggest for color: steep some tea, but leave the leaves out of the soap for a beginner; depending on their skin type, it may end up being too scratchy. In fact, for your student's, I suggest no exfoliant additives. Plain soap is best for a first time soap, IMO.
CO percentage, the highest I would recommend for a beginner is 20%, but if it was me, I'd probably go no higher than 18% (for myself, I go lower still.)
Would HO Sunflower or HO Canola be cheaper than Olive? If so, I'd go with one of them. Not the regular versions because they would raise the linoleic acid content too much.
I am assuming you are talking about the GV shortening with tallow and not the GV vegetable shortening? If you are talking about the vegetable shortening (that's the only one sold at my local Walmart), then the linoleic acid content would be really high in the end product, and I would suggest including a chelator as well to help prevent DOS. I don't personally use Citric Acid, but it would be something your students should be able to find in a grocery store.
Anyway, it is so cool you are going to do a lesson in your home. Good luck and have fun!