This story was about the race that find some flags hidden in the forest. Teacher said that final flag was in the bear's mouth. Children heard a loud sound from the cave and they were afraid of the sound. But David went into the cave alone. And he found the flag. The sound from the cave was the sound on the CD.
I learned that don't be afraid from this book.
Waring, R., & Jamall, M. (2006). The Bear's Mouth. Boston, MA: Thomson ELT.