My wife was going through a pile of papers yesterday and found a dungeon map key that my son had made some time ago. I went through some of my Whitebox campaign notes and found what I think is the corresponding map, at least it has the same number of rooms and the pit trap is drawn next to the right key number. It was probably about four years ago, as it was shortly after this that I gave my kids the tip of choosing monsters close to the challenge level of the party, and you can see this has no such constraints – Sea Serpents, Demons and Yetis cohabit equally with Orcs and Kobolds!
When we first started playing, I told the kids to just pick monsters that they liked from the Swords & Wizardry Monster Book (Word doc). They would create adventures and take turns DMing for me and for each other. Of course at that point I was just happy they wanted to play at all, so I tried to encourage whatever creativity they showed. I have some old maps they drew, but for some reason none of them have the corresponding keys, this is the first map key to turn up. Below is the corresponding map.