Give them a scavenger hunt, depending on their age you can write it on a sheet of paper or even use flash cards or just tell them one item at a time. The idea is to have this game ready before they get to where your going.
Examples:
1. For counting - how many guys have a hat on, or those wearing glasses, or how many babies they see . . .
2. For colors - find someone with a green coat, or a red pair of shoes, or a blue scarf . . .
3. For words - this helps them know their surroundings better too like; exit, telephone, restroom, food, police . . .
4. For people - people watching can be lots of fun (by age, size, male or female, or job) police officer, bus driver, maintenance worker, cashier . . .
5. By size or shape - triangle, circle, square . . .
6. By food or other items found in a food store - this works well if you use coupons, give the child a few coupons where they need to find the item before you buy it.(this can be fun for them too when they find the item and get to pick what kind or color if there is a choice)
7. Money - it is always fun to find lost money on the ground, but you really have to look for it.