Dimension Mix pays tribute to Bruce Haack and Esther Nelson, unlikely partners who created some of the most inventive, adventurous children's music ever recorded. If you missed the duo's mini-revival back in 1999 (and unfortunately, a lot of you did), here are the essentials: Haack, an experimental composer and instrument-maker, wrote the tunes -- rangy, minimal, brain-tickling material that bears little resemblance to contemporary electronic music. Nelson, a school teacher with a commanding voice and a knack for narrative, wrote the lyrics. Together, they challenged their youthful audience to think, to explore, to imagine -- and they did it in unconventional, occasionally amateurish ways, using a medium that even the poorest modern school would sneer at today. Everything that seven-figure budgets, immersive multimedia and licensed characters so often fail to do today, Haack and Miss Nelson accomplished with a room full of cobbled-together electronic gear, a microphone and the earnest desire to connect with kids. Their label, Dimension 5, never made them rich -- again, a failure by modern standards -- but to the kids who enjoyed their music and the teachers who used it to enliven their classes, Haack and Nelson's contributions were priceless.

You'll notice that many of the artists featured here are around the right age to have enjoyed a Bruce Haack and Miss Nelson record during their own grammar school days. Perhaps that's why Dimension Mix's covers (and cover/remix hybrids) are significantly more respectful of the source material than most so-called tributes. Many of the featured artists, Beck and Stereolab among them, completely re-imagine the Haack/Nelson material, with varying results, while studio-centric acts like DJ Me DJ You and Fantastic Plastic Machine sample, reshape and remix the original songs to create more contemporary (but usually less coherent) configurations. The best cuts highlight the universal melodic strengths of Haack's songwriting. Beck's "Funky Little Song", which opens the disc, is a rich, bubbly nugget of Beatlesque pop, complete with a show-stopping falsetto. Money Mark's "Spider" embraces the song's experimental vibe while playing up the lyrics' matter-of-fact campiness, and Chris Kachulis returns to "Listen", the song he wrote with Haack, to give it a thick coating of psychedelic haze. Oranger turn "Catfish" into the most icthyologically instructive power-pop song you'll ever hear, and Danielson Famile transform "Nothing to Do" into a compelling tract on orch-pop eccentricity. On the instrumental front, Stereolab's almost-seven-minute "Mudra" is more interesting and inventive than any of their "proper" new material, and Anubian Lights' "Walking Eagle", which seems to use the original song's vocal, wraps its dense, funky electronic arrangement around spoken-word lyrics about peace-pipe smoking.

If there's a flaw in Dimension Mix's plan, it's the fact that the integrity of Nelson's lyrics is sacrificed to the cut and paste production. Fantastic Plastic Machine's "I'm Bruce" is a prime example: its sampled, manipulated interjections are amusing (especially if you have a friend named Bruce), but the material's depth is lost in all the good-natured goofiness. Likewise, "Walking Eagle" probably wasn't meant to be a stoner rock epic, but that's what it emphasizes. DJ Me DJ You's version of "Soul Transportation" fares better, acknowledging the tune's trippy, reverb-abusing vibe and slaving the cheesy vocals to a breakbeat, but retaining a coherent linear structure.

A portion of Dimension Mix's profits will be donated to various autism chartities. This is not, as others have suggested, a good reason to buy the disc; if you want to contribute to the fight against autism, send a check to a reputable autism charity and don't expect a CD in return. On the other hand, if you're looking for a reason to choose Dimension Mix instead of another, less socially responsible disc, the decision has been made for you. Dimension Mix doesn't always capture the spirit of Haack and Nelson's work, but its eighteen tracks offer plenty of opportunities for glorious imagination.