Later in the episode, he has an even more annoyed expression when Doris calls for him during recess.
The whole thing implies that Timothy and Doris have interacted before the show started, but whatever actually happened to the point where he just goes "Doris." is left to our imaginations.
In the episode where Nora thinks of a birthday gift for Yoko, Nora chooses a box of cereal called "Weeds And Seeds". She normally doesn't like it but buys it for the green glass slipper. She says to her mother she will eat the entire box; cut to Nora taking minutes to eat the entire bowl and box of cereal. The slow music playing sounding like a clock complete with Nora's look of disgust◊ is pretty funny to look at and her chewing the cereal very slowly.
A moment later, he is told to get his head under the water. Claude remains stubborn and refuses until Timothy spots Doris and her mom approaching. Then he quickly dives under the water and stays there until they leave.
During the montage of Timothy helping Claude, they splash Timothy's dad with water; causing him to make a surprised face.
In "The Shutterbug" where Timothy attempts to take a good picture of his class students. Most of the time the photos would either would look awkward or silly. Special mention goes to the scene where Timothy tries to take a picture of Charles and tells him to back away. But at the last second, Charles falls onto the rock tower he made which Timothy immediately takes.
Charles: (In an annoyed tone) You told me to go back too far, Timothy.
One episode starring Yoko involved her trying to grow a Cherry blossom tree. When her mother recommends trying to grow the tree she gives her the seeds or as she calls it "Magic Beans". Yoko then says this silly but cute line as a response.
Yoko: Mama I'm not Jack And The Beanstalk.
"The Welcome Song" at the beginning of the series. Towards the end of the song, Miss Jenkins has everyone go around introduce themselves by name. It ends with Lilly, who seems to think for a second... "Um... Lilly!" Funny, and also a great way to introduce her status as the Forgetful Jones.