Most likely, your students have never heard of the Klondike Gold Rush. Best practices teaches us students learn best when they can build upon existing knowledge. Therefore, it is helpful to first introduce the gold rush to your students before taking them on the adventure. One way to do so is to view the PBS video "Gold."
A trip to the Klondike Gold Rush National Historical Park is also a good way to introduce your students to the gold rush. See Lesson 3