Review and provide feedback

This is a great lesson!

Here are some questions that came to mind as I went through:

Should tests consider the case when a node has a value of nil but still has children? Or would that case never happen in our specific implementation?
Considering the case above, should the difference between a node with a value of nil ( e.g. TreeNode.new(nil, TreeNode.new(5), TreeNode.new(6)) and a nil node (as in node = nil) be addressed somewhere, or do we want to let students "discover" it?
Should we include a section that touches on practical applications of the structure? What are binary trees commonly used for, etc.?
I think a common issue while working with binary trees is balancing/re-balancing after CRUD operations on nodes. Should a second part of this lesson introduce the concept of balancing? Maybe have a couple exercises to practice re-balancing a tree after a node is deleted etc. A third part could then go into ordered trees and have students use the balancing method they implemented in part 2 to re-order/re-balance the tree after an element has been deleted or edited.

DPI-WE / ruby-data-structures-algorithms-find-height-of-binary-tree