A transect is a path across an area. Geographers, both formal and informal, often follow a transect across an area to explore the changes between here and there. Sometimes the changes are close together and dramatic; other times a transect must cover a long distance before yielding a significant change in landform, land use, building style, population density, and so on.
Educators can't always go on actual field trips. Limits in time, spending, and permissions may constrain what a class can do in real life. But a class that knows how to use ArcGIS Online can conduct a virtual transect, looking at many characteristics visible in the field and some that are invisible in the field. The Virtual Transect app shows you how.
First, look at the example, a tiny town in central Washington, then think about building your own. Mark a corner of the school grounds with a map note, then create rings of a distance that one might experience on foot (0.5 miles), by bicycle (2 miles), or in a car (10 miles). Using the imagery layer (as basemap or as an added layer), mark out changes in the land radiating outward. Then add some layers from the Living Atlas to find additional changes in the patterns of land and people.
I did a similar description of this process years ago, when ArcGIS Online was just getting started. It is so much more powerful now, with more data, more analysis tools, more presentation options, more collaboration possible using an ArcGIS Online Organization. These tools let explore, analyze, illuminate, and describe patterns, and then determine actions to make the world a better place. While the best experience is clearly from mixing the real thing with the digital, you can begin right there in the classroom, doing a Virtual Transect.