You did a science experiment back in junior high. Remember? We all did. But it's safe to say that nobody has done a science experiment like Scott Grimes' on Saturday night's edition of "WonderWorks" (8 on WETA and WHMM).

Grimes plays Arlo, a young guy whose bedroom is filled with snakes, caimans, frogs and several other examples of reptilia. A herpetologist, he'd say; a science nerd, you might say. Reptiles are his best friends, his companions.

Actually, Arlo has a real best friend, who has graduated to warm-blooded creatures: girls. He realizes that Arlo is obsessive about his hobby. But the two go way back, so he does his pal one last good deed and fixes the bespectacled, carrot-topped scientist up with a blond cheerleader-type, Susie.

On his way to the movies for the double-date, Arlo discovers an unusual frog for sale in the window of the local pet store. His date money, a $20 bill from his dad (who was ecstatic that Arlo has at last got a date), ends up in the hands of the pet shop proprietor.

The frog, a large Italian model whose favorite ditty is "That's Amore," rides along in Arlo's pocket, ends up in the popcorn and generally ruins the date (a 3-D movie that's funny in its own right). Arlo's friendship with his long-time pal is over. But his relationship with Gus the Frog has just begun.

PBS' "WonderWorks" is a fine series -- it was the umbrella for the Emmy-winning "Anne of Green Gables," for example -- but fans of the program may be amazed at "Frog."

Keep in mind that Shelley Duvall's Platypus Productions, creators of Showtimes's "Faerie Tale Theatre" and "Tall Tales & Legends," did this one as well. Duvall, inducted into the Video Hall of Fame as an innovator in video programming and a member of the board of directors and executive committee for the National Cable Television Association, is executive producer for "Frog." In its way, "Frog" is a fairytale too -- an adaptation of "The Frog Prince" -- even though "WonderWorks" calls it a contemporary comedy.

Duvall, who starred as Olive Oyl in "Popeye" and appeared in "The Shining," "Nashville" and "Three Women" (for which she won the Los Angeles Critics Award and the Best Actress Award at the Cannes Film Festival), appears as Annie, the mother of young Arlo. Annie is a woman who serves wheat germ cobbler, reads palms, creates astrological charts and understands her son's obsession with snakes. Somehow, after watching Duvall's portrayal of Annie, one understands better why her son is the way he is.

Elliott Gould plays Arlo's good-natured father, who'd rather not get involved with reptiles, but who tolerates his only child's obsession. He hopes Arlo will go to college and become a prize-winning scientist.

Amy Lynne is Suzie, the blind date, who agrees to be Arlo's science partner mainly because she knows she'll get a sure A in the course. Susie is more interested in eye shadow than amphibians. Girls who enjoy science will find Suzie an annoying stereotype. But she learns, and in the end, she turns out to be a good sport.

And then there's the frog, Gus, no ordinary fellow, but a real prince of a guy. A Real Italian Prince, he insists, having been turned into a frog 600 years ago by a witch. A kiss from a beautiful woman will release him from the spell, he says, but it's been devilishly difficult to arrange.

Meanwhile, the frog contents himself with talking to his new owner and singing "That's Amore," a talent that comes in handy when Arlo's science experiment, "How Frogs Communicate," is in severe question from the skeptical judges.

Suffice it to say that Arlo ends up with the science prize after all, as well he should; that Suzie sees beyond Arlo's glasses and into his Real Character; and that she does her best to turn Gus the Frog into the prince he insists he is.

Composer Paul Williams, who has sold more than 180 million records and has written soundtracks for several movies, uses a dreadful imitation-Italian accent as the voice of the frog. Obviously, for Williams, "Frog" is a bit of a lark. But when Williams turns up as the vocalist at the family's celebratary dinner, take a good look: By golly, there is a resemblance.