Linda Birtel and I stood in the produce section, where she was taking the simpler approach: Shop with recycling in mind.
This is easy for her, since she sells recycled goods for her King of Prussia company, Allied Waste Services.
She agreed to take me on a field trip, so we'd met at the Genuardi's market in Royersford, where she usually shops.
The produce section, as it turns out, was a good place to illustrate the first rule of "precycling": Don't get any packaging at all. Buy stuff loose.
But to our left was what I expected would be the first pitfall: plastic containers of spinach and salad greens. I've bought them, but I always felt guilty because I didn't think they were recyclable. I'd put the empties in the basement to use as mini-greenhouses for seedlings.
"Actually, they're a No. 1" - recyclable - Birtel said, lifting the container to show me the numeral "1" inside a triangle, a universal recycling symbol indicating what kind of plastic it was. It was so tiny I'd missed it.
Birtel cautioned that recycling programs vary - sorry, you still have to do homework on your local program - but generally No. 1 and No. 2 plastics are accepted in this region.
We passed the cracker, cereal and spaghetti boxes - all fine as recyclable paper, even with the little cellophane windows, so long as you flatten them.
The containers of spray oil and whipped cream are merely glorified cans. Just make sure they're empty.
Halfway through Aisle 4, I caught on that far more than I had thought was recyclable.
It's important that we recycle. In 2006, containers and packaging made up 31.7 percent of the U.S. municipal waste stream - 80 million tons.
"There is a world demand for these products," Birtel said. "By recycling, you're saving a great deal of natural resources."
But in Philadelphia, the household recycling rate is only 8 percent of the waste. Birtel recycles 40 percent.
I had thought packages with food on them couldn't be recycled. Not long ago, I told her, I'd thrown out an empty flour bag.
Just shake it out, she said, and put it with the rest of the paper.
Bottom line: A bit of residue is all right. Goo is not.
I thought I'd get her on the soup and milk boxes. Aren't they foil-lined? "Just paper," she reassured me.
But even experts don't know what to do with everything.
Birtel picked up a noodle bag and turned it over, looking for clues, then shrugged. "It's not marked. I can't tell."
Birtel's rule of thumb: If the plastic is pliable - like bread bags and veggie bags - it can go in the storefront bins for recycling plastic check-out bags, which aren't accepted for curbside recycling.
If it crinkles or crunches, it's probably not recyclable.
Anything that's mixed materials in one package - foil and paper, say - can't be recycled.
And, oh, those foam containers under almost all the meat. Not recyclable.
The orange juice aisle was interesting: glass, plastic or box?
The waxy coating on the box has a moisture barrier that doesn't break down easily in a paper mill. Glass is all right. But plastic is better because it's worth more to people like Birtel.
As for the Parmesan, it turned out nearly all the containers are recyclable.
But by the time my lesson was over, one clear choice emerged.
Buy a lump of the stuff and grate it yourself.
Contact staff writer Sandy Bauers at 215-854-5147 or firstname.lastname@example.org. GreenSpace runs every other Monday. To read recent columns or her GreenSpace blog, go to http://go.philly.com/sandybauers.