We do not cover sunscreens in our courses as we do not recommend that you make DIY sunscreens. They are a very different type of product that require rigorous testing before you can claim they offer sun protection.
We have written an article that explains more here: DIY sunscreen: why you should NOT make your own sunscreen
www.schoolofnaturalskincare.com/why-you-should-not-make-diy-sunscreen/