If you know a kid and don’t take her to Jim Henson’s Fantastic World sometime soon…well, that kid that has every right to sever all ties to you. Although anyone will find the exhibit illuminating—in fact, most of the sketches, print work and ephemera will be of interest mainly to nostalgic adults—a child will reap great rewards from a grownup willing to point from a drawing to a full-scale puppet and note how this became that. You want proof of how far your imagination can take you, kid?

Henson began work in Washington, D.C. in 1955 and eventually built Kermit the Frog from two ping pong balls and the fabric from his mother’s old coat. But he also, as this installation shows, let his creative talents roam free until they connected to something…and then moved forward, restlessly driven, over and over again. Look for accomplished New Yorker-style cartoons, black-and-white TV commercials that managed to simultaneously sell a product and snap across a joke within about 5 seconds, and the kicky, kooky Time Piece, an experimental film from 1965 (screened next to shots of scrupulous storyboards for it) in which Henson, in own words, “was playing with a flow of consciousness form of editing” that resembles a kind of absurdist jazz.

Henson left such a paper (and celluloid and puppet) trail behind him that only several tours of the show could take it all in. There’s the original sketch for Cookie Monster with the note “able to feed himself” written beside it; an illustration of how to operate Big Bird; and several pen or watercolor drawings from the 1960s featuring creatures only Henson—or contemporaries like Seuss or Sendak—could have dreamed up (Big Uglies, Elf Rockettes, Frackles, et al). Puppets and preparations for TV’s Fraggle Rock and the landmark fantasy film The Dark Crystal are on display for fans of Henson’s later work.

And, of course, there are Muppets here and there. Most of them—from Ernie and Bert to the fabulous Mahna Mahna and his Snowth backup singers—in protective glass cases. But the highlight of the exhibit is The Mudgarden Experience, an interactive room that shows you how a Muppet performance works. You choose one from a handful of Muppet likenesses of Seattle musicians (Kurt and Jimi would, I hope, be thrilled) and duck beneath a stage to watch a monitor while you make the Muppet you’re holding above you lip-synch to a selection of songs (including Van Morrison performing “It’s Not Easy Being Green” and Cake doing “Mahna Mahna”).

I say you because this is the one instance where you’ll want to shove the kid out of the way and have your own fun. There have to be some benefits to growing up.