When I was in college, the folks bound for teaching k-12 math were in the lower half of the math classes I took. Ditto history. From talking with people, I assume that was generally the case with a few exceptions like the arts or coaching.
Does a k-12 curriculum require a college degree anyway?
What crippling debt? You can get a BA degree in Elementary Education that will be accepted by all 50 states in the US for under $20k [1]. (You can cut that almost in half if you can handle a heavy course load).
[1] https://www.wgu.edu/online-teaching-degrees/elementary-educa...