I honestly feel sorry for any mother who has to have a child in her class. To automatically assume she knows the best for every child, even above that child’s own mother is a horrible attitude.

I’ll confess, I’m usually not a super fan of homeschooling. However, my knowledge of it is mostly based on someone in my family. She also homeschools her (many many) children. She does not have a teaching degree, she does not have time to give them all the attention they need. The older ones have fallen behind, but in their state they just need to say “we’re done” and it counts as a high school diploma. The parents also want to limit their children from anyone and anything that is not godly enough for them, severely stunting their mental and social growth. It sounds like your situation is the opposite of everything I have experienced with this family.

Also, it’s nobody’s business what you do, especially your MIL. It’s rich she thinks she knows better than you despite your education and has no issues repeatedly telling you. I guess it’s time to just stop telling her anything about your children’s education. She has absolutely no say in the matter and she needs to understand that.