Teams should do the entire activity at least three times. On a chalkboard or overhead projector, record each team's final sand levels for the entire class to see. This part of the activity can be completed as a class or with teams. Instead of teams of two, try teams of four. One student holds the tube, one drops the dowel, one measures, and one records the data and does the math.
Students can take turns doing each job.
You can further reveal the special strength of sand by substituting other materials in the tube and comparing the results. Understand that only a small amount of sand is needed to prevent cave-ins. Understand that these features of sand make it a good material for building small burrows.