Let me rephrase the question:
If a teacher can't teach all subjects, then how could we expect a student to learn all subjects?
This is the answer:
Teacher's knowledge about a particular subject = Approximately 80% - 99% of the whole knowledge.
When the teacher teaches the students, then the teacher teaches them according to the syllabus. So, the students only learn around 1% of the knowledge.
Let say there are 10 subjects need to be covered by the teacher and learned by the students.
When the teacher needs to teach all subjects = 80% X 10 = 800%
However, when the students learn all subjects = 1% X 10 = 10%
Now, back to the question above.
If a teacher can't teach all the subjects (means a teacher cannot provide 800% of the knowledge, at least 80% can be provided) but we can expect a student to learn all subjects because they learn only for 10% from the whole knowledge!
Just remember this, dear students - YOU WILL NEVER LEARN THE WHOLE SUBJECT in school.
Am I answering your question? Hopefully, yes.
