After the introduction, students are at the helm and need to start doing something. The application gives them an array of tests and/or other information sources such as interviews with experts or fictional characters involved in the case. Students can investigate each one in any order, but after finishing the test, they come back to this navigation screen to head off in a new direction. Few INDIE applications have had strong elements of time, so time spent in each test or the order in which they are done is important only in a domain-specific way, such as in a medical domain where students should run the least painful or invasive tests first.
For many applications, these tests are available at some sort of virtual location or in a structured notebook. Volcano's navigation screen is a map of Mt. Andrews. Students can travel to six points of interest that are labeled to show the students what they're going to do at each site.
The authors of Volcano struggled with the design of this screen quite heavily--there is a delicate balance from the teaching point of view between letting the students do any test first and scaffolding students into doing the tests in a pedagogically important order--in essence, students aren't volcanologists, so how would they know what to do first? The compromise here is to give options to ask for help if they need it, but also support sophisticated and naive theories about volcanology at the same time, so students can either ask for help or (more likely) just leap into things and try to figure it out as they go along.
The first time students travel to a site (e.g., click on one of the site buttons), they are given an introduction from the guide in the form of a transitional movie, who tells in more detail what to expect at each site and what kinds of tests have already been run. Also, in some of these transitions, students meet locals who are worried about the volcano erupting. During the original design phases, Volcano authors didn't have the locals, but the scenario turned out to seem very abstract without seeing the faces of the people students are trying to help. They also are there to emphasize how important it is for the out-of-town experts to get their diagnoses right--the citizens tell the (probably dire) consequences of getting the diagnosis wrong.