Where can 11-13 years old find jobs?
The best job I had before I was 16 was a once a week paper route. Often times, the major local paper has a free "A La Carte" issue (with sales, coupons, recipes, etc.) that comes separately if a resident does not have an actual paper subscription.
You just have to rubber band or bag the papers and deliver them one day a week. I was a lucky girl to have my mom drive me around the block and I'd just chuck them out the passenger window onto people's driveways.
It was only 4 times a month and I got close to $200 a month for it.