My classmate told me I should always say, "With all due respect," or "I politely disagree," when disagreeing someone - especially an educator - in order to avoid being perceived as rude.
Teacher: This class always infuriates me. Most of you are either absent or late for my class. I will give you all failing grades in this subject!
Me: With all due respect Ma'am, many of my classmates actually do attend your class, and arrive early, to learn something about your subject. I think you should take all those students who attend your class on time and daily, into consideration.
Teacher: There's a higher incidence of suicide in men than women because men choose to hide their suffering or pain without telling anybody.
Me: Ma'am, I politely disagree with this opinion. According to the most recent studies of the American Psychiatric Association about suicide, more women attempt suicide than men, although men seem to be more successful in their attempts, resulting in more fatalities.
Can you suggest some polite variations?