Hello!

I am currently taking the Penn Foster course on opticianry and ... I have to be honest, it leaves a lot to be desired, including a textbook it constantly references but apparently does not actually include. 

One of the hardest things for students of opticianry to grasp is the math and other concepts involved in calculating lens powers at various meridians, transposing formulas and so on.

Laramy K Opticianworks offers their own classes, but I think if anyone would understand that there are people who cannot afford even $10/month, it’s the wonderful people at Khan Academy. You are the only reason it’s financially feasible to homeschool my daughter.

Penn Foster links to your course on trigonometry, but I think it would be great if there could be even just a few videos that address these formulas directly. 

Thanks for your consideration, and for everything you do.