When I was the Webelos leader, we were doing a unit on shopping and budgeting. I took the kids on a field trip to the grocery store and gave them each $5 — with the instruction to "buy stuff that you would want to eat." It had to be wrapped or canned.
The local food bank was right across the street from the grocery store. When we finished shopping, we took the food that we bought and donated it. I explained to the kids that the people who need the food bank aren't any different from you and me. The kinds of food that you like to eat are the kinds of food that they like to eat. I hope it made a difference.