Food (adults)
Baked Ziti
Salad
Meatballs
Rolls
Mini Kaiser Sandwiches

Food (kids)
Mac n cheese
Chicken Fingers
Mini Sandwiches (creamcheese & jelly etc)

Fruit platters

You will find that the kids eat the adult food and the adults eat the chicken fingers. So this is an all in one estimate, and I am assuming the kids are mostly 4th grade and under.

Baked Ziti
Mac n cheese
You need a total of 15-16 pounds pasta, you can divide it, or just make mac and cheese- everyone likes it. Good recipes on this site

Salad- Do for 100 from the plan for 100 page. Put dressing on the side- some kids do eat salad, especially with ranch dressing. Have at least 5 pounds baby carrots.

Meatballs- 1 pound per 6 if small, per 5 if large. 3 quarts sauce per 10 pounds.
Chicken Fingers- 2 per person for everyone unless very large, then do 1 per little kid, 2 for everyone else.

Mini Kaiser Sandwiches
Mini Sandwiches (creamcheese & jelly etc)
You could skip these and just put out bread and rolls (12 pounds) and 2 or 3 gallons of sandwich spreads/fillings, such as a platter of 5 pounds sliced cheeses, the cream cheese whipped soft, jam, tuna salad, egg salad, maybe a non-peanut nut butter? They are fiddly and time consuming to make, and don't keep very well.

Fruit platters
Thorough discussion of amounts and choices on the fruit tray page. Watermelon is still available and a popular choice. Plan for 125 adult servings.