Map tools are found in the lower left corner of the map view, next to the Add Feature button. The following tools are available: measure, base map switcher, and fit.
The measure tool allows you to make quick distance or area measurments on the map. To measure something's distance from your current location simply tap once on the map. To measure the distance between two point simply place two fingers on the map at the desired points. To measure area simply place 3 or more fingers on my map. Tap the measure button again to exit measure mode.
Use this feature to quickly toggle between base maps. You can also toggle Overlays (such as Contour Lines) on and off in this dialog.
Tapping the fit button will zoom and center all points, lines, and polygons allowing you to see your entire project.