Is it permissible to sell academic materials obtained from an educational institute, or to rephrase and sell them to students, without obtaining the permission of the subject's teacher?

If the teacher reserves the right to photograph or print the material, then it is not permissible to photograph or print it except with his permission. However, if he allows the students to photograph or print it, then you may do so. Similarly, if the students or others are the ones who collected and printed the lectures, then the right belongs to whoever expended effort in compiling and authoring.