This section is the result of discovering a side-subject of how a trail was "marked," for travellers, much as our mile-markers along the Interstates now.  Geographical and Geological landmarks, the stars, some small villages and the man-made and placed "Milestone Markers" of engraved stone would be how the emigrants would find their way along the "blazed" trail.
One interesting point in how the National Trail was truly a real highway in pioneer days was that stumps were only allowed to be up to 14" tall.

In this section, students could help to design "Milestone markers" out of any appropriate material including plaster of Paris, or even cardboard.
A simulated trail could be created on the school grounds with groups of students following the trail with the "Milestone markers."  The markers could have coded messages about the point they represent.

To modernize the trail, make use of a Magellan GPS device, and create a school grounds trail with points mapped on the device.  See if the students can read the latitudes/longitudes of the Magellan.
They will be able to.  I've done it down to 2nd grade.
Same principle as the old days, but a bit more modern.