Question

Which sentence in this excerpt from Leo Tolstoy’s The Death of Ivan Ilyich suggests that Ivan Ilyich and his wife couldn’t even agree on how to raise their children?
He attained this by spending less and less time with his family, and when obliged to be at home he tried to safeguard his position by the presence of outsiders. The chief thing however was that he had his official duties. The whole interest of his life now centered in the official world and that interest absorbed him. The consciousness of his power, being able to ruin anybody he wished to ruin, the importance, even the external dignity of his entry into court, or meetings with his subordinates, his success with superiors and inferiors, and above all his masterly handling of cases, of which he was conscious—all this gave him pleasure and filled his life, together with chats with his colleagues, dinners, and bridge. So that on the whole Ivan Ilyich's life continued to flow as he considered it should do—pleasantly and properly.

So things continued for another seven years. His eldest daughter was already sixteen, another child had died, and only one son was left, a schoolboy and a subject of dissension. Ivan Ilyich wanted to put him in the School of Law, but to spite him Praskovya Fedorovna entered him at the High School. The daughter had been educated at home and had turned out well: the boy did not learn badly either.

Answer 1

The sentence in this excerpt from Leo Tolstoy’s The Death of Ivan Ilyich that suggests that Ivan Ilyich and his wife couldn’t even agree on how to raise their children is the penultimate one - Ivan Ilyich wanted to put him in the School of Law, but to spite him Praskovya Fedorovna entered him at the High School.
It shows that they disagreed on where their children should be educated. 

Answer 2

Ivan Ilyich wanted to put him in the School of Law, but to spite him Praskovya Fedorovna entered him at the High School.

This sentence explains one of the disagreements Ivan Ilyich had with his wife about their children. Ilyich wants his son to attend the School of Law and she enrolled him at the High School. This sentence follows the statement that their son was a "subject of dissension". Dissension means disagreement or point of argument. This sentence specifically gives an example of what one of their disagreements is about.