You don't send newborns out to fight wolves. The problem isn't the other kids in the school, the problem is that some teachers are wolves and will mock and ridicule any kids with a testimony of Jesus.
I would recommend that Christians homeschool their kids through JHS. Math at that point is only algebra. If you coordinate with your church and other parents you can have your kids learn an instrument, be in the choir, and perhaps become a black belt in Karate for their PE. For drama they can be in the church plays. Then all you need in addition to that is to read books, one good sized book a week from the time they are in 4th grade. By the time you finish 8th grade it is 250 books which can include a list of the 100 books recommended for kids to read.
However, I would also train the kids to be a witness for the Lord and put the goal in front of them to evangelize the high school that they will go to. You could pray over that high school in home school and prepare them in the word to be mocked and ridiculed till like Paul they would see this as a great honor. Two kids fully trained up in the word could completely evangelize a high school over 4 years. The training would also require that you teach the kids the law and they be fully prepared to offer a defense to anyone who tries to threaten or intimidate them.