(Not a Teacher)
"I recalled his diligent teaching...."
--- 'Teaching' is a gerund here, so it does not take adverbs.
"....to help students look for their innocent ego."
--- I don't have the faintest clue what you mean by 'innocent ego'. Do you mean something like 'innate curiosity' or 'desire to learn'?
"Therefore, he often took us
studentsout of the classroom to expose us to thenature in hopes of finding the true purpose of learning as well.
--- The inclusion of 'students' is superfluous and breaks the flow of the sentence. 'Expose' needs an object here. I prefer the sound of 'in hopes of' to 'in the hope of'. I feel you wanted something like 'true ' or 'primary' instead of 'initial'.
- For Teachers