Halloween isn't only for collecting M&M's and wearing Glee Cheerios costumes. More groups are promoting it as a teachable moment for kids to do good.

Kids are being encouraged to swap old costumes rather than buy them, recycle candy wrappers and urge adults to support "fair-trade" chocolate and children's programs.

"We're saying to kids: Get out there and be an activist," says Caryl Stern, president of the U.S. Fund for UNICEF. By raising just $1, she says they can buy clean water for a child for 40 days.

Trick-or-Treat for UNICEF, the 61-year-old grandma of such efforts, is going high tech. The door-to-door donation box now has a tag adults can scan with a smartphone to donate $10. Supermodel Heidi Klum touts another fundraiser: Kids can upload photos and design costumes online.

Other groups have jumped in:

More kids will "reverse trick or treat" by handing out bite-size chocolates made without forced child labor and a card lauding fair-trade cocoa. Equal Exchange, a worker-owned co-op, says it has had 21 percent more requests for its fair-trade chocolate kits this year than in 2010.

More families are swapping costumes as the number of registered swaps at libraries, churches and schools in the USA and Canada jumped from 70 last year to more than 170, says Corey Colwell-Lipson, founder of Green Halloween.

More schools are collecting candy wrappers to send to TerraCycle, a recycling company that gives donors money for charitable use. It has received 1.2 million candy wrappers so far this year, more than double its 2010 total.

"At first, kids were like, 'It's just trash' ... but when they saw how it added up, they caught on," says Daniele Clark, a fifth-grade science teacher at Spicer Elementary in Haltom City, Texas. She says students have collected enough wrappers to raise $842 so far -- enough to send eight kids to a three-day science camp.

The trend irks some. Grace Melton at the conservative Heritage Foundation writes that parents might not want their kids raising money for UNICEF if they knew that, in her view, it has shifted from protecting children's health to promoting reproductive rights. Hershey, the target of many fair-trade cocoa advocates, argues it has done much to help cocoa communities in Africa.