In terms of Harper Lee's To Kill a Mockingbird, I can't write two diary entries for you, but how about I give you some ideas and you write them up!

In Chapter 11, Mrs. Dubose, as the children pass in front of her house on the way to town, insults Atticus. Jem, who is generally more mature than the younger Scout, returns from town, still furious over her statement, and he destroys all of her camellia blooms.

When Atticus gets home, Jem has to go speak to Mrs. Dubose by way of apologizing and making amends. It is decided that he has to read to Mrs. Dubose every day. Scout goes too. Mrs. Dubose still insults Atticus, but as time goes on, Jem matures to the point that he can keep a blank, polite look on his face without showing any emotion in response to her insults. He matures enough to learn self-control, which is an enormous accomplishment, especially with Mrs. Dubose.

The incident can also deal with Mrs. Dubose and what Jem thinks of her when he realizes she needed his company to break a morphine addiction before she died. Atticus calls her the bravest woman he ever met, and it terms of the incident, Jem might write about how such a small thing as reading was so important to her. He might even realize that she was nasty partly because she was in so much agony from her illness. Perhaps he realizes that he did something good for someone else, even if it came out of something nasty.

Of course, when Scout and Jem are almost killed at the end of the story (Chapter 28), you could write a diary entry by Jem about what he learns when he wakes up, his disappointment of missing Boo, and who had attacked them...and who had saved them.

I think if you stick to one of these things, you should be fine. Hope this helps.