Where: Bright Angel Trailhead → Second Tunnel → Yavapai Geology Museum → evening ranger program
What: Today you go below the rim — a little. The Bright Angel Trail starts right in the village (behind Bright Angel Lodge) and the classic family objective is the Second Tunnel: 1.5 miles roundtrip, descending through two rock tunnels blasted in the cliff face, with the canyon opening wider with every step. This is the taste of inner-canyon hiking that satisfies kids completely — they've been inside the canyon now, and the bragging rights are real. The NPS rule to drill into everyone: every step down must be climbed back up, and the climb out feels twice as long. (With very small legs, the First Tunnel at 0.36 miles roundtrip is the gentler turnaround the NPS recommends for small children.) Turn around while the kids still have spring in their step; the tunnel is the goal, not the mile marker. Carry twice the water you think you need — the trail is exposed, the air is dry, and there's no water on this upper section.
Back at the rim by lunch, the afternoon is for the Yavapai Geology Museum (if Day 1's walk didn't include it) and downtime — the lodge pool, a nap, the Junior Ranger booklet. Evening belongs to the ranger program: check the park newspaper or visitor center for the night's topic and location (McKee Amphitheater in summer, Shrine of the Ages in shoulder seasons). Ranger talks run about an hour, they're free, and the good ones — condor reintroduction, canyon geology, night skies — hold kids' attention better than any screen. It's also where Junior Rangers get sworn in and receive their badges, which for a 6-to-12-year-old is roughly equivalent to a knighthood.
When: On the trail by 8am (beat the heat and the mule trains); ranger program after dinner
Route note: Trailhead to Second Tunnel is 0.75 miles each way, ~620 ft elevation change. The trail is wide and well-maintained but unshaded — hats and sunscreen essential.
Pro tip: Never attempt to hike to the river and back in one day — the NPS explicitly warns against it, and rangers rescue hundreds of unprepared hikers yearly. The tunnel turnaround is the family play; the canyon will still be there when the kids are older.