|Number in season:||4B|
|Original Airdate:|| October 18, 2012|
April 10, 2013 
|Written by:||P. Kevin Strader|
|Storyboard by:||Gerry Capelle|
"Night of the Tibble"
D.W. enlists the help of Brain to determine if her sister Kate is above average, below average, or just average-average.
The show begins with Arthur, Binky, Kate, Pal, and Mei-Lin watching Andy and Company. Then D.W. shows up and takes the remote to which Arthur and D.W. start fighting. Then they were interrupted by Mei-Lin who was playing the piano, saying hello, and making Binky burp. So D.W. tried to get Kate to say hello, but she didn't understand. So D.W. explained Kate's problem to Arthur. Arthur was trying to say she will learn, but D.W. was arguing. Kate and Pal figure out that her brain is causing D.W. to go crazy.
The next day, D.W. and the Brain were trying to get Kate from below average to above average, but she makes noise instead with the blocks. When D.W. is going crazy again, Kate shoots at D.W. In D.W.'s room, she is planning to get Kate above average. Nadine explains it won't be easy, but D.W. states that Kate needs her. In the bathroom, Kate states that D.W. needs her. Pal objects that it would take ages to find the right combination of sounds, but Kate declares that she can't see D.W. suffer like this.
The next day, Arthur, D.W., Kate, and Pal visit Binky and Mei-Lin. D.W. tries to get Kate to make noises, but Kate didn't understand her. Mei-Lin gives advice to Kate. Then Kate put the pig's legs under the cat's body. D.W. tries to correct Kate, but Arthur told her to lave Kate alone. Binky then says babies do the most amazing things, to which Mei-Lin texts hello on her calculator. Later, Kate copied D.W., but she can't spray D.W. again. Instead, she said D.W.'s name, to her excitement. Then Pal shows up and Kate states that she cured D.W. by copying her. Pal then states that people are the most illogical, strange and frustrating creatures on the planet and that they do understand how to make a top-notch hambone, finishing the episode.
- In "Mei Lin Takes a Stand", Kate is the one who is more advanced and growing up faster. In this episode, it is the complete opposite.
- Kate imagines herself as a teenager differently than in "Paradise Lost."
- In this episode Kate hear the others speak as "Blah-Blu-Blehs" like Pal's dog hearings. But, on an interesting note, Mei Lin seems to understand the others (to Binky mostly) since Mei Lin is growing and understanding Binky very well.
- Just like in "Breezy Listening Blues," Brain's intelligence test is to fit different shapes into the correct holes. But this time, he acknowledges that one test is not enough for a final conclusion.
- D.W. calls Arthur a "broken baby", referring to "D.W.'s Time Trouble".
- Andy and Company makes a second appearance; only in this episode, it is called "Alfred", and Andy and his sister's clothes were changed to resemble D.W. and Arthur's.