Your kids are plenty old enough to start enjoying the great out doors. Our daughter started camping with us at 2-years old. She's three now and loves going on nature walks with me. I've already taught her the whole "hug a tree, blow your whistle" routine if she gets lost and we practice it. She's learned which are "owie bugs" and which bugs she can pick up. ID-ing poison ivy is going slow but if it's around I point it out to her and explain touching it is worse than a bunch of fire ant bites. So far she hasn't touched it.
Sometimes I get a little frustrated when we are heading to a beautiful spot be she decides she wants to spend 20 minutes playing in a sandy part of the trail, but if it's fun for her she'll want to go back.
You need to bring a lot of water, snacks, sunblock and bugspray. Kids can seem fine one second and suddenly become dehydrated, low blood sugared, burnt and bit really fast. Keep an eye on them and they'll be fine.
-Blast