I homeschooled all three of mine so I’ll venture a few possibilities. Homeschooled our son 5th through High School and our daughters the whole way. There are a lot of approaches to homeschooling and I’ve seen a few successes, but some epic fails as well. A lot depends on the homeschool educator’s intent. I went into it because I was confident in my ability and had a keen desire to do everything possible to do it right. I also loved being with my children and watching them love learning. Unfortunately, that is not always the case. Some parents do it as a way to escape the oversight of others and the school, to avoid the homework and carpools etc. and the children are educationally neglected. Some call themselves unschoolers and this casts a bad light on the true unschoolers who approach education via means other than traditional books, rote learning and typical schedules, but they work very hard to cover all that by other methods. It is also known as ‘child led’ learning. The child follows their interests and learns. It can leave huge gaps in my opinion. It wasn’t my cup of tea, but I won’t judge.
According to ET’s sister, the mother was uninvolved, but the children went to church a lot. It may be possible that they went to Homeschool Co-op classes. Those are classes taught by other homeschool educators or teachers hired by the Co-op to teach once a week. I personally participated in about four different ones and wasn’t terribly impressed by the actual academics, but we used them as one of our vehicles for socialization. If ET and her sibs belonged to a couple of Co-ops, she may have been able to get enough to get her by. Or it is possible that ET was given access to the material and taught herself. I have seen some very self-motivated homeschool students do that.
There is also Virtual School and this may be the most likely way ET was homeshooled. Many states have an option through public school called Virtual and it is free. It is delivered over a computer platform and every class imaginable is offered. There is regular contact with a teacher via phone conference with the student and the parent. They are, in general, good classes. We did a few virtual courses in our homeschool as well. One of mine did 2 years of Latin and my girls did 2 years of Spanish. They also did the driver training (book portion). One did a year of guitar as well. They offer all the traditional courses too, through advanced literature, history and mathematics. We covered those at home, so didn’t partake. Many homeschoolers take a full virtual load though and that is how they choose to do the homeschooling. Basically, the parent is there to make sure they are on the pc and moving in a productive direction. It is also easy for parents to fall down on that task and if that is the case, the student could get behind. I’ve seen many students burn out on a full virtual school load. IMO there is a lot of ‘fluffy, time wasting’ type activity thrown in and it adds up to a lot of time spent stuck in front of a pc.
All this said, I think that however ET did it, she did manage to get enough to get close to grade level when she was placed in public school. According to her sister, she was doing quite well in Spanish. I was impressed! I let virtual cover that one.

I think ET sounds like a motivated learner and a bright student which makes what TC did all the more reprehensible and vile. I would like to hear more from ET’s sister on how they approached homeschooling, method and curriculum choices.