What you’re experiencing is a goal limit in Frontierville. You can only have five goals at a time. This might be the reason why you don’t have the Schoolmarm goals even though you already constructed a School House in your homestead.
Frontierville is not broken. You just have to complete your present goals before you can get new ones. Some goals are chains, which mean you unlock a new goal after completing one.
The Schoolmarm goals were recently added to Frontierville. This is one of the reasons why some lower level players have it and you don’t. Don’t think that you’ll miss it entirely. Just focus on your current goals and new goals will unlock in the future.
So don’t worry if you still don’t have School House goals. At least you’ll still have time to collect ribbons required for those lessons.