This book is a great science fiction book about a two little kids exploring caves. This could be a great book used for writing as well to engage the reader and then have the student write about what they may find in a cave. This could be used in all grade levels k though 5th.
Anecdote time: My dad went through a spelunking phase in his younger years, which made for fantastic stories about tight spaces, slippery stones, and creepy creatures. He still has an unnatural ability to move quickly, keep his balance, and not lose his footing.
Back to the review. Roma Gans does a wonderful job of explaining how caves form and what spelunkers do in them. The illustrations work well, really capturing how caves cut into the landscape. This would be a great introduction to caves for younger children.