Ok, I will be out on a limb here, but have to agree a lot with the school. Milk or milk products are causitory in type 2 diabetes, has been linked to type 1 as well even when mothers breastfeed if the mother's diet has milk products in it, it is a proven fact backed by scientific studies. . Why don't people know this? Because the Dairy industry does not want them to. After a person is weened, they do not need milk, water is the only necessity.
I do not know what yogurt was taken, but many of the little ones in the cute little containers are loaded with sugar. Most kids would not eat yogurt that is plain, but if you want to give the kids yougurt, then use a plain or Greek yogurt, adding berries, or other fruits yourself. It will probably take the kids some time to adjust to the flavor. We have all been educated with our palates to prefer sweet tastes, some of this is ingrained within our DNA, but a good bit of it has been trained in us by the food industry. Even using artificial sweeteners wakes up this craving in us.
If you check with the stats, even our military is now worried that most of our generation of kids will be too fat and unhealthy to be of any use. Research is showing more and more that it is our diet that is the cause of many of our chronic diseases. I wish the government had been less enthralled to the meat and dairy industry during my growing up years. It took a lot of trial and error to make my taste buds adjust to what is a healthier diet for me
As to what to feed or pack for lunches, homemade soups of lentil, or vegetable that you can season yourself with spices homemade peanut butters with a bit of honey, fresh fruits, raw veggies with a hummus dip, but the foremost thing to do is ask yourself, If I know what I am feeding my kids now will make them sick ten or twenty years from now, would I be willing to change what I am feeding them now, even if it is inconvenient, or they may object for awhile?