Noach vs. Avraham 

The Torah describes Noach as a tzadik in "his generations." What do the multiple generations refer to? Rashi cites the midrash which comments that this pasuk is meant to contrast the generations of Noach and of Avraham. The midrash explains that some interpret the comparison to Avraham's generation as reflecting favorably on Noach: Noach was righteous in his generation and would have been even greater had he lived in Avraham's time. Others interpret the comparison to Avraham's generation as a critique of Noach: Noach was considered righteous in his own generation, but had he lived in Avraham's generation he would not have been considered all that special.  When I learned this midrash with my eleventh grade Chumash class we asked: what would motivate the midrash to offer the critical view of Noach? After all, God speaks directly to Noach, deems him worthy of being the father of the human race, and establishes a covenant with him!

Perhaps the comparison of Noach to Avraham is meant to highlight their very different responses when informed by God of impending doom. When Avraham was told that the destruction of Amorah was imminent, he expressed concern for its citizens, begging God not to destroy the city. In contrast, when Noach was told of the flood, he dutifully built the ark and sealed his family away from the rest of the world. Rabbi Yaacov Yosef of Polnoye, a student of the Baal Shem Tov, explained that when the Torah says את האלוקים התהלך נח, that Noach walked with God, the Torah is actually criticizing Noach's behavior! He may have walked with God, but he took absolutely no interest in his fellow man.