1. Tree
• A set of linked nodes that form a hierarchy
• There is a root node at the top
• Each node may or may not have children
• In some types of trees a node may have any number of
children and in other types the number of children are
controlled
• The nodes at the bottom most level are called leaf nodes
• The nodes between the root and the leaf nodes are called
internal nodes
• A subtree is a portion of a tree that can be viewed as a
complete tree in itself.

2. Tree
• Traversal
– Breadth first
• Visit all the nodes at a given level
before going deeper
– Depth first
• Visit nodes as deep as possible
first

3. Trees
• Binary tree
– Each node has at most two
children

4. class
title
instructor
semester
assignment*
title
instructions
grading
student*
name
first
middle?
lastfeedback?
grade?