The fact that the kids are headed back to school this week makes us think about learning, and yet ... it's hard to let go of the outdoors. We know they'll be looking out the windows, wishing they could hop on a bike and pedal away, or hike into the woods and escape from those non-air-conditioned classrooms for a few more weeks. Here are four metro-area trails where you can see nature and learn a little something, too.

Walter Orr Roberts Weather Trail: An easy, hikers-only, 0.4-mile loop at Boulder's National Center for Atmospheric Research, with a 75-foot elevation gain and signs along the path that explain all things weather. Abundant with wildflowers and offering great views of the Flatirons, it's ideal for little ones. spark.ucar.edu/weather-trail

South Platte River Trail: Everyone is welcome along this easy, paved trail, which runs for 30 miles from Denver and features interpretive signs about the American Indians who once inhabited the area, as well as wildlife, dinosaurs and fellow travelers throughout history. denver.org/what-to-do/sports-recreation/denver-bike-trails

Walden Ponds Wildlife Habitat: The hike around the Boulder ponds is an easy, 2.5-mile loop (add another mile for the Heatherwood Link), and the whole complex is a smorgasbord of wildlife — beaver, deer, foxes and so many birds (water and song varieties), plus clear views of the magnificent Indian Peaks — that you can read about en route. Bikes, horses and leashed dogs are allowed. bouldercounty.org/os/parks/pages/waldenponds.aspx

Eldorado Springs Trail: It's a little more than 5½ miles each way to cover the moderate, year-round trek into Eldorado Canyon near Boulder. Learn about trains from the placards, and, if you're lucky, see one pass through. Horses and dogs but no bikes allowed. parks.state.co.us/Parks/EldoradoCanyon/Trails

Kyle Wagner: 303-954-1599, travel@denverpost.com or twitter.com/kylewagnerworld