Once your address is verified and there is an opening in your area, Nielsen will send you a UPC scanner. Each time you come home from the store (grocery, etc.) you scan all of your items in. Nielsen Home Scan keeps data and research on consumer buys.
This is a great project for your kids. Every kid will think those scanners are cool and want to do their own scanning.
Nielsen pays you back for your efforts with gift cards and shopping in their rewards section.