| Season 4, Episode 4B|
|Original Airdate:||September 27, 1999|
|Written by:||Joe Fallon|
|Storyboard by:||Jeremy O'Neill|
D.W. discovers a passion for science, but her explanations for questions like why the sky is blue don't sound right to Arthur.
The intro begins with Brain explaining the Earth's rotation that causes day and night when Arthur stops him, saying they don't understand what he's saying. We then see he's talking to Baby Kate and Pal.
After the title card, Arthur and Buster were watching NOVA when D.W. distracts them, annoying Arthur. Later, Arthur and Francine were playing catch when Francine spelled a word D.W. couldn't understand. Later, Arthur wants to see the sci-fi movie 5,000 Explosions and a Supernova. D.W. wants to go too, but Arthur wouldn't let her. In Arthur's room, D.W. talks to the Brain, annoying Arthur. Brain showed D.W. science fun while Arthur is doing his homework. At dinner, Arthur blamed D.W. for bothering the Brain. D.W. denies it. After dinner, D.W. wants to go to the exploratorium, but Arthur wouldn't let her.
The next day, D.W. started her own world of science and wouldn't let Arthur in, but Arthur loaned her 73 cents, a ring, a torn horse sticker, and a sourball. D.W. presents her exhibit wrong, much to Arthur's annoyance.
So Arthur and the Brain take D.W. to the exploratorium. D.W. then states that her theory that Arthur would beg to take her to the exploratorium was correct much to Arthur's shock, ending the episode
|Major Roles||Minor Roles||Cameos|
- D.W. pronounced exploratorium wrong in this episode.
- The "NOVA" television program that Arthur and Buster watch is a real show. Not to mention the fact that it was from PBS (Public Broadcasting Service), the same company that provides Arthur.
- When The Tibble Twins raise their hands, Tommy has Timmy's blue scarf and Timmy has Tommy's red scarf then in the next shot of the Tibbles they have their regular scarves again.
- This is one of the few episodes that show a real life TV show interlaced with the animation.