This tree looks weird
The neat holes in rows are made by the Yellow-bellied sapsucker. They do not harm the tree. Here is info from our website that you might like to share with your students: http://extension.umd.edu/hgic/woodpeckers-and-sapsuckers
The freshly pecked holes may be from woodpeckers.
The black color of the trunk can be caused by an insect infestation higher on the tree. Lecanium scale, a type of insect, protects itself with a covering and sucks nutrients from the tree. Here is info from our website: http://extension.umd.edu/hgic/armored-and-soft-scales-trees-and-shrubs Scroll down to "Soft scale on broadleaf trees and shrubs" and you'll see lecanium scale. These scales excrete "honeydew" which contains sugar. A black mold grows on the honeydew, known as sooty mold. We think that is what has turned the trunk black as it rains down from above. If you can, look up high on the tree. You're welcome to send us photos if you can see the scale.