This weekend I read a book by a highly-revered spiritual teacher, and he said that after his enlightenment he initally tried to teach students everything, but as he got older, he felt like he should only teach to a certain point. After that, if a student was curious, he was willing to tell them anything, but he used the students’ curiosity as a way to separate those who were really interested from all others.
Back in the days when I taught Java and OOP courses, I also started by teaching everything, including Design Patterns, but then I realized that that was too overwhelming. So then I also only taught certain topics if a student asked about them (or later, if we offered an advanced course).
So, if you’re ever a student in any subject, I encourage you to ask questions. You never know what a teacher is willing to tell you, if only you’d ask. ;)