We shut off lights to make sure we don't waste electricity, we don't let the water run while we brush our teeth, and we start driving our car immediately so that we don't waste gas by letting it "warm up".
But do I "allow" some waste in our house. When it comes to the kids, you bet I do.
Here are some wasteful practices in the Wanna-Greenie household:
If my son wants to do a "project" that involves him using an entire roll of Scotch tape, I let him. He's not just pulling all off the roll for fun; in his mind he is creating something and goshdarnit, you should see some of the stuff he has taped together.
My kids enjoy water play - this means that on occasion I will fill up the kitchen sink to the brim. Sometimes twice.
I really don't consider any uneaten food "waste" per se. We compost most everything we (don't) eat. In addition, if my son "wastes" an orange during his attempts to make fresh-squeezed orange juice or if my daughter likes shelling beans instead of eating them, so be it.
How do you "allow" your children to waste resources?