Tim Hesterberg has been a long time advocate of the use of the bootstrap. In this article, he provides a nice general overview of the bootstrap with examples of how it works in several common settings that might be covered in an introductory level statistics class.
Hesterberg, Tim (2014) What Teachers Should Know about the Bootstrap: Resampling in the Undergraduate Statistics Curriculum. Available at http://arxiv.org/abs/1411.5279.
You can find an earlier version of this page on my blog.