Aloha. So, is this a new endeavor? If you got all the chickens at once and you want to be safe, you can get a small bag of medicated feed at the feed store. There is chick starter and even pellets that are medicated. I, myself, do not want my animals, or children or anything, on medication for life. But a small (10 lbs) sack would ease your mind and get rid of any parasites. After that, a good book or some old codger who has been raising hens in your area for a million years is your best source for care. The best things for hens are clean balanced food, fresh water, a bit of greens, a chance to dust and scratch for bugs and get a little exercise, and fresh air and a clean coop or enclosure.
You have children...teach them to sit down for 5 minutes each day and KNOW their flock. Sit down a short distance away and simply observe. Teach them; show them how to notice every chicken and every part of that chicken. In just a couple of weeks a smart kid will start noticing the quirks, behaviors and habits of each chicken. Then the 5 minutes becomes the daily physical check-up. You will be surprised. A change in poop, a watery eye, a dominant one suddenly passive and quiet--the kids will notice and report and you'll be on top of any problem. Good luck.