when you know in advance you won't have time to prepare a meal?
For instance, if one of your kids has an activity right around dinner, how do you plan ahead so you don't have to purchase fast food?
It might sound bad, but I just make sandwiches. They're easy, cheap and perfect on-the-go food. That way, they can grab them out of the fridge and even eat them in the car if necessary. Plus, it isn't too hard to make them healthy. Turkey on whole-wheat with some lettuce, a slice of cheese (and tomato if you like it) and a little yellow mustard... yum. Hits every food group!
I keep a snack bag in the car. It has bottled waters, granola bars, jerky and a bunch of other shelf-stable snacks like push-packs of applesauce. Last night I had to pick-up DD from school and drive across two counties to meet hubby so we could see a house. By the time we were done with that, DD was starved and dug through the snack bag on the hour+ drive back home so I could make dinner.
I also try to plan for them by freezing meals. We have also had sandwiches for dinner or an extra snack to tie us over until we did get home. If it was an activity where we had to wait around for one of them to finish, I might even bring a thermos with soup for the girls to eat if it were right at dinner time. The one with the activity could eat in the car on the way home...