The class started off the afternoon with a presentation on global warming. At one point a student inquired on how scientists know that the earth's temperature is changing faster now than it ever has in 10,000 years. Kent, one of the instructors, explained that there are many different kinds of records scientists can look at in nature, such as gas concentration in glaciers. After this brief presentation, the class made a model concerning tree limits and global warming. They had to research online in order to make their model. This lasted them for the rest of the class time.