Where does T'Challas sister learn science from

Well first they may not exchange information, but that doesn't mean they don't receive information from sources. We don't know if Wakandans have access to the internet. I pretty sure with how technical they are they can without being detected. And also you don't know how good the schools are. Just because they don't connect with the outside world that doesn't mean the have crappy schools. Who is to say that 200 years ago they had a scientist that figured out E=mc2. They are a few decades past us in science. It's not like Einstein was the only person who could've come up with his Theorys. If you don't want to got the route that others in Wakanda have figured out most what we know now without contact with outside world we can go with Srinivasa Ramanujan. In real life Srinivasa had no formal training in Advance Mathematics. He made substantial contributions to mathematical analysis, number theory, infinite series, and continued fractions, including solutions to mathematical problems considered to be unsolvable.