St. Matthew Island is the story of the US Coast Guard establishing a navigation post on an island, and putting 29 reindeer on the island as a backup food source. The island is shortly decommissioned, and the population of reindeer takes off exponentially.
Stuart McMillen has a great comic describing the event that you can view and scroll through. You used to be able to download the comic in PDF form for free, but it looks like Stuart has started charging $2 for a download. You can still scroll through it to show your class without paying.
As an introduction to Exponential Functions, run through this comic with your class. Have students graph the data points as they appear in the comic, and make predictions. There’s a great tie-in to biology here.