If someone were to wander around the University of Wisconsin grounds asking students about the one thing they remember from their childhood, chances are many of the responses would include books like “The Cat in the Hat,” “Fox in Socks” and “Green Eggs and Ham.”

The timeless books by Dr. Seuss – real name Theodor Geisel – remain a classic part of our childhood, and the film companies have obligingly tapped into that market with movie adaptations, often with varying degrees of success (“The Cat in the Hat,” anyone?).

In the case of “The Lorax,” directors Chris Renaud and Kyle Balda (“Despicable Me”) have done a generally commendable job of taking the source material and building a classical story around it, but they lose much of what made “The Lorax” such a powerhouse in the world of children’s publishing in the first place.

The trademark Seussian elements are still there – anthropomorphic animals (who spontaneously break out into song), bright colors everywhere and not a straight line in sight. Walking fish hum the “Mission Impossible” theme song, and the marshmallow-loving woodland critters are lovable and rendered beautifully.

However, that’s where the similarities end to the original source. “The Lorax” takes the sparse story, perfect for a children’s storybook, and weaves an epic – if not slightly contrived – yarn of adventure, love and the classic “weak-triumphs-over-evil” line that fits into a running time of less than one hour and 30 minutes.

If the film is to be believed, the tale presented in the original storybook was just one part of a larger drama. The story of “The Lorax” begins with Ted (Zac Efron, “Liberal Arts”), a boy from a town called Thneedville where there are no trees nor grass and everything is manufactured. Fresh air is sold by the bottle by a giant corporation run by Mr. O’Hare (Rob Riggle), a tiny man with a big temper. Ted is head-over-heels in love with Audrey (Taylor Swift, “Valentines Day”), a quirky and freedom-loving girl who dreams of seeing a real, living tree.

And so the stage is set for what many people have deemed impossible: crafting a real, screen-ready story out of a Dr. Seuss book, which is often known for its non-sequitur storytelling and open endings – if there is a story at all.

Surprisingly, the story works. There are identifiable main characters, the evil guy is evil, the good guy is good, the Lorax himself (Danny DeVito, of TV’s “It’s Always Sunny in Philadelphia”) is wonderful and full of life, and we finally get to see the Once-ler’s face (Ed Helms, of TV’s “The Office”).

But a big part of the enduring charm of the original book was that it didn’t do any of those things. There were no main characters. The Lorax was a serious, humorless character who really did speak for the trees. The only part of the Once-ler we got to see (was he even human?) were his green arms, which were revealed in the movie to be nothing more than really long gloves.

But more than that, the book left readers pondering, thinking. Much like the book, it doesn’t have a happy ending – on the contrary, it had a positively depressing ending, with the anonymous boy left in charge of a single truffula seed and the words “unless.”

It made readers wonder what would happen afterward, whether or not the story ended happily – and that’s why “The Lorax” was able to be such powerful book in less than 50 pages.

And just like that, the film loses a lot of what made Dr. Seuss’ original book so thought-provoking in the first place. The film comes off as a fun-sized version of Al Gore’s “An Inconvenient Truth,” without the facts.

A lot of the ambiguity – the deliciousness that made us fall in love with Seuss’ famed book – has been sucked out of the film version, replaced with a shallow story about saving the townspeople of Thneedville from its self-imposed isolation.

There’s nothing wrong with environmental activism – in fact, it’s a very important issue that should have wider discussion – but “The Lorax” attempts to graft Greenpeace-esque morals with spontaneous musical numbers, with the end result being a somewhat sloppy work that is never quite sure what it’s supposed to be doing. “The Lorax” comes off as merely another PSA about the dangers of materialism and resource exploitation, and in the process loses much of the uniqueness that made the original work a nuanced bastion of sustainable living.

3 stars out of 5