HS Junior in AP Computer Science

Hello everyone. My son is a junior in high school and is taking AP Computer Science and this last semester got an A+ in the class. This is the highest computer science class the school offers and he is interested in finding additional courses either free or relatively inexpensive for him to take either next year or later this year. Does anyone have any suggestions that would help him get some cybersecurity knowledge or just extending his knowledge of computer …

computer computer science cybersecurity science