Often families post online asking for recommendations for a good hike for little ones close to the Anchorage area. My first suggestion is always Reflections lake.
Out of all the hikes we have been on Reflections Lake is likely the one we have visited most often. It is always at the top of my list when suggesting hikes for small children.
Reflections is a 1 mile Loop hike around Reflections Lake and boats amazing views or Pioneer Peak. The trail is mostly flat. Where there are hills, there is usually a path to the side that offers a less steep option. There are multiple rocky/muddy beaches along the trail, benches, and a viewing tower about halfway around. The parking at Reflections Lake is free and there are outhouses available close to the trailhead.