I have three kids, ages 12, 9, and 7. We go outside together for outdoor time mid-morning everyday. Sometimes, we walk around, look for critters, or just sit on the back deck and have a snack. I let them decide. They usually end up finding something that captures their interest, get running through the woods, etc. Then, later in the afternoon, they usually are back out there.
With the little ones that you have, obviously you have to be out there with them, so maybe the mid-morning break for all of you would work?
Diana