Waste not....

I wouldn't really call us frugal. We make lots of careful choices with our money but we also spend a lot on things we value. But we're not wasteful.
Last night at dinner I piled a plate full of lettuce and baby tomatoes, carrot slivers and broccoli for Little Berry and myself. She enjoys dipping her veggies in cream cheese and so I reached for the container to give her a separate dish of it for dipping.
I turned around to find her shaking the rest of the bag of lettuce into the garbage. She looked so proud of herself, like she was helping me. I think in her mind she was being genuinely useful. But it got me wondering:

How do we teach children about not being wasteful?

-Give them age-appropriate tasks they can complete. When we're leaving rooms or the apartment I will pull a chair up to the light switch and ask Little Berry to turn the lights off for me. She enjoys it and it gets her practicing the habit of noticing such things. Make it fun or a game and they will remember it.
In the case of food, I will start involving her more. Perhaps from now on she can be in charge of putting the lettuce into a Tupperware container or picking just as much as we need to eat at a time from our container garden of lettuce.
- Volunteer with them doing something like picking up trash in the park or cleaning out their toy box to take items to a local thrift store. This way they get to see their efforts pay off and see an alternative to simply throwing things away.
-Use less myself and model appropriate behavior. I am guilty of some times pouring a glass of water down the sink if I am finished. We can use that water on our plants or start leaving a bowl of water outside our apartment building for smaller creatures in this summer heat. The fact is- everything we do means something to our children.
-Be wary of what I am modeling as "trash" to my daughter. Recycling is something kids can get involved in and teaching about waste isn't just for the environment. It's ideal for the health of your family as well because your choices will lead to a healthier childhood for your little ones and a better parenthood for you.
-Talk about it, read about it, make up your own stories about it. This one is a given and probably easiest of them all. But just talking about it means nothing if you don't also model the behavior.
-Relax. Sometimes kids are wasteful. They don't comprehend that splashing in the sink is wasteful- to them it's pure bliss to have chilly streams of water everywhere. Sometimes you need to let go of the rules and just enjoy the moment.

What are your tips? How would you approach wastefulness with your child/ren?