[Maymayfor]

Learning about riba is not haram, as long as you dont put it into practice. Many times, schools teach about un-islamic things, but its not haram to sit through these courses, as long as you dont let it affect you in a negative. I took Health Class in high school last year, and it was probably the most immoral and filthy class I ever took. They'll tell you things like, "Masturbation is a completely normal and healthy habit" and "Its perfectly healthy to date and have sexual relations as a teen, but remember, always use a condom!" and "Drugs and Alcohol can kill you, but you should still do them moderately"
But its still not haram to sit through these type of classes, as long as you dont start listening to the teacher.

As for teaching about Riba, im not sure. Personally I dont see anything wrong with it, as long as you're not taking part in Riba, or encouraging it. But wait for more knowledgeable brothers to answer