When you are lost in the wilderness and disoriented, 100 yards is a lot. I have spent years in the northern woods and have come to the conclusion that I am a very poor woodsman. To a 12 year-old......... Plus, know one knows at the moment if he was on the move - which seems likely.
Our local Boy Scout camp has a dining hall with a 100' long front porch. Early for a meeting there one time, I noticed a sign that read something like - learn your pace, 100 feet. In a minute or two it hit me. It takes me 44 steps to walk 100 feet. I thought at the time, what a cool thing to teach children.