Kajiwara Sora and her friends in the art club sketch what they see and make observations on life. That's really all there is to it. Sketchbook features beautiful scenery, plenty of feel-good moments, and cats. Can't forget the cats. It's just the kind of show that puts a smile on your face. A fine example of a Slice of Life series. An anime, titled Sketchbook ~full color'S~, aired in 2007.
Sketchbook provides examples of the following tropes:
Adaptation Distillation: The manga consists largely of Japanese word jokes, but only some surrounding Kate found their way into the anime.
Cat Smile: Kurihara Nagisa is never seen without one
Character Development: EVERY single character goes through this, but it applies most to Sora. Compare to how she introduces herself to Natsumi, Hazuki, and Kate to how she introduces herself to the waitress at the diner in the last episode.
Demoted to Extra: Tsukiyo Ooba's role, already not that big in the manga, has been assigned only a few seconds of spoken dialogue in the anime—which is a shame, since she is a genuinely funny character.
Cute Kitten: A Five Cat Cast by episode 11 — Mike, Haa, Grey, Kuma, and Buchi. There's a few other cats in the manga too.
Kindhearted Cat Lover: Sora doesn't have a cat, though a few of her friends do, but is your typical Friend to All Living Things...but the kid keeps giving them expired food, which her brother calls her out on. so this might be subverted in the cats' eyes until she realizes her error.
Large Ham: Tsukiyo tends to be... rather melodramatic
Schoolgirl Series: There are a few male characters, but both adaptions, especially the TV one, focus on Sora, Hazuki, and Natsumi. Kasugano's Man Child personality and the focus on the wackiness of the art room cement this series as a Schoolgirl one.
Shout-Out: To ARIA, with the "president" of the Aria Company as the mascot of a bowling center. Also, at the very end of the last episode, there's a picture◊ of President Aria and Akari meeting Mike and Sora.
A discussion about Paracerura tattaka turns into a shoutout to Hamtaro in the manga.
Surprisingly Good English: Kate: and her cat Buchi. Good job for the creators for picking someone who can speak very good English to voice her, unlike Ai Yori Aoshi. Since when Americans speak bad English?