A short, easy trail, and the kids will love seeing the petroglyphs.
Don't touch or deface the petroglyphs.
This is a very small trail to some Indian petroglyphs. The area is remote by park standards, but close to Terlingua. You'll rarely find other people along this trail even with the proximity to Terlinqua/Study Butte.
To get to the start of this route, if coming from the west, exit of the Park on 118/Maverick Road take a right on Indian Head Road. It's a dirt road just north of Big Bend Resorts and Adventures. Follow the course of the road for a little over a mile. It will wind back to the left and then loop back to the right. The roac will end at the fence to the park. The fence is merely a marker for the park boundary, and there is a gate which is always open (In fact, there is no gate on the gate posts).
Once you go through the gate you'll see faint trail that goes down a grade. There will be some postings by park in the first 200 yards or so about the petroglyphs and the history. Hugging the hill (Indian Head) on the left, continue roughly east and pay attention to the boulders at base of the hill to find the petroglyphs. Rough Run will be to your right (south) and you should be able to see the Chisos off to the east south east.