From known to unknown is a fundamental maxim of teaching.
This pedagogical principle suggests that learning is most effective when new information (the unknown) is built upon the foundation of what the student already understands (the known).
A teacher should first assess the students' prior knowledge and then connect the new concepts to their existing mental framework.
Starting from the unknown would be confusing, while staying at the known would result in no new learning.
Thus, the correct process is to guide students from the known to the unknown.