diff --git a/lib/tree.rb b/lib/tree.rb
index c0d4b51..63cbeed 100644
--- a/lib/tree.rb
+++ b/lib/tree.rb
@@ -16,51 +16,155 @@ def initialize
     @root = nil
   end
 
-  # Time Complexity: 
-  # Space Complexity: 
+  # Time Complexity: O(log n) - side eliminated
+  # Space Complexity: O(1)
   def add(key, value)
-    raise NotImplementedError
+    new_node = TreeNode.new(key, value)
+
+    if !@root
+      @root = new_node
+    else
+      current = @root
+      until !current
+        if current.key < new_node.key
+          if current.right
+            current = current.right
+          else
+            return current.right = new_node
+          end
+        else
+          if current.left
+            current = current.left
+          else
+            return current.left = new_node
+          end
+        end
+      end
+    end
   end
 
-  # Time Complexity: 
-  # Space Complexity: 
+  # Time Complexity: O(log n) - side eliminated
+  # Space Complexity: O(1)
   def find(key)
-    raise NotImplementedError
+    return nil if !@root
+
+    current = @root
+
+    until !current
+      return current.value if current.key == key
+      
+      if current.key < key
+        current = current.right
+      else
+        current = current.left
+      end
+    end
+    return nil
   end
 
-  # Time Complexity: 
-  # Space Complexity: 
+  # Time Complexity: O(n) - all nodes visited
+  # Space Complexity: O(n) - array size based on node amount
   def inorder
-    raise NotImplementedError
+    return [] if !@root
+    values = []
+    inorder_key(@root, values)
+  end
+
+  def inorder_key(current_node, array)
+    if !current_node
+      return array
+    else
+      inorder_key(current_node.left, array)
+      array << {key: current_node.key, value: current_node.value}
+      inorder_key(current_node.right, array)
+    end
   end
 
-  # Time Complexity: 
-  # Space Complexity: 
+  # Time Complexity: O(n) - all nodes visited
+  # Space Complexity: O(n) - array size based on node amount
   def preorder
-    raise NotImplementedError
+    return [] if !@root
+    values = []
+    preorder_key(@root, values)
+  end
+
+  def preorder_key(current_node, array)
+    if !current_node
+      return array
+    else
+      array << {key: current_node.key, value: current_node.value}
+      preorder_key(current_node.left, array)
+      preorder_key(current_node.right, array)
+    end
   end
 
-  # Time Complexity: 
-  # Space Complexity: 
+  # Time Complexity: O(n) - all nodes visited
+  # Space Complexity: O(n) - array size based on node amount
   def postorder
-    raise NotImplementedError
+    return [] if !@root
+    values = []
+    postorder_key(@root, values)
+  end
+
+  def postorder_key(current_node, array)
+    if !current_node
+      return array
+    else
+      postorder_key(current_node.left, array)
+      postorder_key(current_node.right, array)
+      array << {key: current_node.key, value: current_node.value}
+    end
   end
 
-  # Time Complexity: 
-  # Space Complexity: 
+  # Time Complexity: O(n) - possible to visit each node
+  # Space Complexity: O(1)
   def height
-    raise NotImplementedError
+    return 0 if !@root
+    height_helper(@root)
+  end
+
+  def height_helper(current)
+    return 0 if !current
+    left = height_helper(current.left)
+    right = height_helper(current.right)
+
+    if left < right
+      return right + 1
+    else
+      return left + 1
+    end
   end
 
   # Optional Method
-  # Time Complexity: 
-  # Space Complexity: 
+  # Time Complexity: O(n) - all nodes visited
+  # Space Complexity: O(n) - array size based on size of tree
   def bfs
-    raise NotImplementedError
+    return [] if !@root
+
+    values = [{key: @root.key, value: @root.value}]
+    bfs_helper(@root, values)
+  end
+
+  def bfs_helper(current, array)
+      if current.left
+        array << {key: current.left.key, value: current.left.value}
+      end
+      if current.right
+        array << {key: current.right.key, value: current.right.value}
+      end
+      if !current.left && !current.right
+        return array
+      end
+      if current.left
+        bfs_helper(current.left, array)
+      end
+      if current.right
+        bfs_helper(current.right, array)
+      end
   end
 
   # Useful for printing
   def to_s
     return "#{self.inorder}"
   end
-end
+end
\ No newline at end of file
diff --git a/test/tree_test.rb b/test/tree_test.rb
index 8811f14..15fb9ef 100644
--- a/test/tree_test.rb
+++ b/test/tree_test.rb
@@ -32,6 +32,7 @@
   end
 
   describe "inorder" do
+
     it "will give an empty array for an empty tree" do
       expect(tree.inorder).must_equal []
     end
@@ -44,8 +45,8 @@
     end
   end
 
-
   describe "preorder" do
+
     it "will give an empty array for an empty tree" do
       expect(tree.preorder).must_equal []
     end
@@ -69,6 +70,16 @@
     end
   end
 
+  describe "height" do
+    it "will give height of 0 if empty tree" do
+      expect(tree.height).must_equal 0
+    end
+
+    it "will return height value for non-empty tree" do
+      expect(tree_with_nodes.height).must_equal 4
+    end
+  end
+
   describe "breadth first search" do
     it "will give an empty array for an empty tree" do
       expect(tree.bfs).must_equal []