It's fantastic that you're keeping your kids active! Are your kids underweight/normal weight/overweight? I'm not a nutrition expert, but there are a few tips and resources that you can use.
As for meals....
Breakfast - ALWAYS, always, always start with breakfast! This is the most important meal of the day for them! Try to have a balance of fruit and/or veggies, whole grains, and some protein.
Snack - At school, they should probably have a small snack if they have the opportunity to in the morning.
Lunch - Again, try to balance between fruits/veggies, whole grains, and protein.
Snack - After school, this snack will probably need to be bigger than the morning snack to give them energy for sports
Dinner - Again, try to balance between fruits/veggies, whole grains, and protein.
Try to have them drink mostly water (it's cheaper than juice or soda!), and plain milk or milk alternative (never flavored). They are kids, so obviously there are occasions where it's fine to just be kids and drink sugary drinks, but it's good to try to only have sweet drinks as a treat, not an everyday thing. Never get kids, or yourself for that matter, into the habit of drinking sports drinks. There are very few people in the general population that actually need these. You have to be a high level athlete or be training at a high intensity for longer than 60 mins to even be considereing sports drinks.
Jamie Oliver has been a great advocate for children and what they eat.... Here is a link to some recipes on his site:
Jamie Oliver's Food Revolution | Recipes | Jamie Oliver (US)
If you scroll down a bit, there are some links to blogs on the right hand side of the screen... I briefly glanced at a couple ("Food for my Family" and "This Mommy Cooks) and they seem like they could be really helpful for thinking of good, healthy ideas for the family. And coming from people with families, it's nice to know that they probably understand what you're going through.
I don't know where you live, but you can look at government sites for dietary recommendations. Here is the link to the Health Canada guidelines for children:
http://www.hc-sc.gc.ca/fn-an/food-guide-aliment/choose-choix/advice-conseil/child-enfant-eng.php
This is another canadian site, but you can sign up for free weekly meal plans if you want... this is a site that I use for gluten free ideas. The ones in the right hand column are free, the others you have to pay for:
http://www.soscuisine.com/meal_plan_directory.php?sos_l=en
I hope that helps a bit!
