Relevant digital map exploration
Google Earth provides a number of learning ("exploration") units that provide context and relevance to different map features. This is an amazing feature. It also allows for interdisciplinary lesson planning. For example, there is a great feature that takes students on a visual tour of medieval castles which is accompanied by an explanation of how math factors into defense planning. Finally, and perhaps of most interest to teachers, there is a project tool that allows students to mark and label the map. Teachers could find many useful applications for this to facilitate student collaboration, communication, creativity, and critical thinking. For example, you could have students identify locations on the map where civilizations first emerged and then compare and contrast their geological features in preparation for a group presentation or classroom discussion.
There is a written tutorial, which is helpful. However, to Google Earth's credit, it is also an incredibly intuitive tool as well. It would be very easy for a teacher to explain how it works and then turn their class loose on an activity.
As far as relevance, this is great. Although I have a love for physical, foldout maps, they are archaic. As somebody who used maps extensively in my previous work prior to becoming a teacher, the feature of Google Earth are very similar to the features a student would likely use in the real world if geography factored into their work.
All of that said, this tool isn't going to do the heavy lifting in regard to pedagogy. Geographical content and technology is here in abundance, but a teacher is going to have to generate a plan for how to integrate this into their lesson (barring the "exploration" activities mentioned above, which are more fleshed out). So, if you want this to facilitate critical thinking, you're going to have to come up with the questions (or previously taught the students how to generate relevant questions on their own).
How I Use It
Google Earth provides a digital, highly detailed map of the entire globe. It provides a bird's eye view and also allows students to zoom down to a highly detailed 3-D view of almost anywhere in the world (I'm sure there are limits to this, but I have not found them). Political boundaries are also labeled (for example, the boundaries of the 50 US states are marked and each state's name is clearly identified). However, this is also customizable. You can select the geographical feature you desire to be depicted or labeled. There is a "search" feature which takes you to the location you enter (for example, "United States" or "Chicago"). There is also a distance measuring tool.