diff --git a/lib/tree.rb b/lib/tree.rb
index c0d4b51..fa9d683 100644
--- a/lib/tree.rb
+++ b/lib/tree.rb
@@ -1,13 +1,13 @@
 class TreeNode
   attr_reader :key, :value
   attr_accessor :left, :right
-
-   def initialize(key, val)
+  
+  def initialize(key, val)
     @key = key
     @value = val
     @left = nil
     @right = nil
-   end
+  end
 end
 
 class Tree
@@ -15,50 +15,141 @@ class Tree
   def initialize
     @root = nil
   end
-
-  # Time Complexity: 
-  # Space Complexity: 
+  
+  def add_helper(current_node, key, value)
+    return TreeNode.new(key,value) if current_node.nil?
+    
+    if key < current_node.key
+      current_node.left = add_helper(current_node.left, key, value)
+    else
+      current_node.right = add_helper(current_node.right, key, value) 
+    end
+    
+    return current_node
+  end
+  
+  # Time Complexity: O(log n)
+  # Space Complexity: O(log n)
   def add(key, value)
-    raise NotImplementedError
+    new_node = TreeNode.new(key,value)
+    
+    if @root.nil?
+      @root = new_node
+    else  
+      add_helper(@root, key, value)
+    end
   end
-
-  # Time Complexity: 
-  # Space Complexity: 
+  
+  # Time Complexity: Best: O(log n), Worst: O(n)
+  # Space Complexity: O(n)
+  def find_helper(current_node, key)
+    return if current_node.nil?
+    
+    if key < current_node.key
+      current_node.left = find_helper(current_node.left, key)
+    elsif key > current_node.key
+      current_node.right = find_helper(current_node.right, key)
+    else
+      return current_node.value
+    end
+    
+  end
+  
   def find(key)
-    raise NotImplementedError
+    return if @root.nil?
+    
+    if @root == key
+      return @root.value
+    else
+      find_helper(@root, key)
+    end 
   end
-
-  # Time Complexity: 
-  # Space Complexity: 
+  
+  # Time Complexity: O(n)
+  # Space Complexity: O(n)
+  def inorder_helper(current_node, list)
+    return list if current_node.nil?
+    # left side
+    inorder_helper(current_node.left, list)
+    # middle node
+    list << { key: current_node.key, value: current_node.value }
+    # right side
+    inorder_helper(current_node.right, list)
+    return list
+  end
+  
   def inorder
-    raise NotImplementedError
+    return inorder_helper(@root, [])
   end
-
-  # Time Complexity: 
-  # Space Complexity: 
+  
+  # Time Complexity: O(n)
+  # Space Complexity: O(n)
+  def preorder_helper(current_node, list)
+    return list if current_node.nil?
+    # middle node
+    list << { key: current_node.key, value: current_node.value }
+    # left side
+    preorder_helper(current_node.left, list)
+    # right side
+    preorder_helper(current_node.right, list)
+    
+    return list
+  end
+  
   def preorder
-    raise NotImplementedError
+    return preorder_helper(@root, [])
   end
-
-  # Time Complexity: 
-  # Space Complexity: 
+  
+  # Time Complexity: O(n)
+  # Space Complexity: O(n)
+  def postorder_helper(current_node, list)
+    return list if current_node.nil?
+    # left side
+    postorder_helper(current_node.left, list)
+    # right side
+    postorder_helper(current_node.right, list)
+    # middle node
+    list << { key: current_node.key, value: current_node.value }
+    
+    return list
+  end
+  
   def postorder
-    raise NotImplementedError
+    return postorder_helper(@root, [])
   end
-
-  # Time Complexity: 
-  # Space Complexity: 
+  
+  # Time Complexity: O(n)
+  # Space Complexity:O(n)
+  def height_helper(current_node)
+    if current_node.nil?
+      return 0
+    else
+      left = height_helper(current_node.left)
+      right = height_helper(current_node.right)
+      
+      if (left > right)
+        return left + 1
+      else
+        return right + 1
+      end
+    end
+  end
+  
   def height
-    raise NotImplementedError
+    if @root.nil?
+      return 0 
+    else
+      height_helper(@root)
+    end
   end
-
+  
   # Optional Method
   # Time Complexity: 
   # Space Complexity: 
   def bfs
     raise NotImplementedError
   end
-
+  
   # Useful for printing
   def to_s
     return "#{self.inorder}"
diff --git a/test/tree_test.rb b/test/tree_test.rb
index 345bf66..347f50c 100644
--- a/test/tree_test.rb
+++ b/test/tree_test.rb
@@ -2,7 +2,7 @@
 
 describe Tree do
   let (:tree) {Tree.new}
-
+  
   let (:tree_with_nodes) {
     tree.add(5, "Peter")
     tree.add(3, "Paul")
@@ -12,111 +12,112 @@
     tree.add(25, "Kari")
     tree
   }
-
+  
   describe "add and find" do 
     it "add & find values" do
       tree.add(5, "Peter")
       expect(tree.find(5)).must_equal "Peter"
-
+      
       tree.add(15, "Ada")
       expect(tree.find(15)).must_equal "Ada"
-
+      
       tree.add(3, "Paul")
       expect(tree.find(3)).must_equal "Paul"
     end
-
+    
     it "can't find anything when the tree is empty" do
       expect(tree.find(50)).must_be_nil
     end
   end
-
+  
   describe "inorder" do
     it "will give an empty array for an empty tree" do
       expect(tree.inorder).must_equal []
     end
-
+    
     it "will return the tree in order" do
       expect(tree_with_nodes.inorder).must_equal [{:key=>1, :value=>"Mary"}, {:key=>3, :value=>"Paul"}, 
-                                       {:key=>5, :value=>"Peter"}, {:key=>10, :value=>"Karla"}, 
-                                       {:key=>15, :value=>"Ada"}, {:key=>25, :value=>"Kari"}]
-    end
-  end
-
-
-  describe "preorder" do
-    it "will give an empty array for an empty tree" do
-      expect(tree.preorder).must_equal []
-    end
-
-    it "will return the tree in preorder" do
-      expect(tree_with_nodes.preorder).must_equal [{:key=>5, :value=>"Peter"}, {:key=>3, :value=>"Paul"}, 
-                                        {:key=>1, :value=>"Mary"}, {:key=>10, :value=>"Karla"}, 
-                                        {:key=>15, :value=>"Ada"}, {:key=>25, :value=>"Kari"}]
-    end
-  end
-
-  describe "postorder" do
-    it "will give an empty array for an empty tree" do
-      expect(tree.postorder).must_equal []
-    end
-
-    it "will return the tree in postorder" do
-      expect(tree_with_nodes.postorder).must_equal [{:key=>1, :value=>"Mary"}, {:key=>3, :value=>"Paul"}, 
-                                         {:key=>25, :value=>"Kari"}, {:key=>15, :value=>"Ada"}, 
-                                         {:key=>10, :value=>"Karla"}, {:key=>5, :value=>"Peter"}]
-    end
-  end
-
-  describe "breadth first search" do
-    it "will give an empty array for an empty tree" do
-      expect(tree.bfs).must_equal []
-    end
-
-    it "will return an array of a level-by-level output of the tree" do
-      expect(tree_with_nodes.bfs).must_equal [{:key=>5, :value=>"Peter"}, {:key=>3, :value=>"Paul"}, 
-                                   {:key=>10, :value=>"Karla"}, {:key=>1, :value=>"Mary"}, 
-                                   {:key=>15, :value=>"Ada"}, {:key=>25, :value=>"Kari"}]
-    end
-  end
-  
-  describe "height" do 
-    it "will return 0 if tree is empty" do 
-      expect(tree.height()).must_equal 0
-    end
-
-    it "will return the nuber of nodes in the longest path" do
-      expect(tree_with_nodes.height).must_equal 4
-      tree_with_nodes.add(60, "sam")
-      tree_with_nodes.add(58, "penny")
-      tree_with_nodes.add(65, "sam")
-      expect(tree_with_nodes.height).must_equal 6
+        {:key=>5, :value=>"Peter"}, {:key=>10, :value=>"Karla"}, 
+        {:key=>15, :value=>"Ada"}, {:key=>25, :value=>"Kari"}]
+      end
     end
     
-    it "will give the correct height of a binary search tree" do
-      tree_with_nodes.add(30, "Tatiana")
-      expect(tree_with_nodes.height).must_equal 5
-    end
-  end
-
-  describe "delete" do
-    it "can delete a note in the tree" do
-      # Arrange & Assert
-      expect(tree_with_nodes.find(15)).must_equal "Ada"
-
-      # Act
-      tree_with_nodes.delete(15)
-
-      # Assert
-      expect(tree_with_nodes.find(15)).must_be_nil
-    end
-
-    it "will return nil if the node is not in the tree when it's deleted" do
-      # Arrange & Act
-      answer = tree_with_nodes.delete(47)
-
-      # Assert
-      expect(answer).must_be_nil
-      expect(tree_with_nodes.find(47)).must_be_nil
-    end
-  end
-end
+    
+    describe "preorder" do
+      it "will give an empty array for an empty tree" do
+        expect(tree.preorder).must_equal []
+      end
+      
+      it "will return the tree in preorder" do
+        expect(tree_with_nodes.preorder).must_equal [{:key=>5, :value=>"Peter"}, {:key=>3, :value=>"Paul"}, 
+          {:key=>1, :value=>"Mary"}, {:key=>10, :value=>"Karla"}, 
+          {:key=>15, :value=>"Ada"}, {:key=>25, :value=>"Kari"}]
+        end
+      end
+      
+      describe "postorder" do
+        it "will give an empty array for an empty tree" do
+          expect(tree.postorder).must_equal []
+        end
+        
+        it "will return the tree in postorder" do
+          expect(tree_with_nodes.postorder).must_equal [{:key=>1, :value=>"Mary"}, {:key=>3, :value=>"Paul"}, 
+            {:key=>25, :value=>"Kari"}, {:key=>15, :value=>"Ada"}, 
+            {:key=>10, :value=>"Karla"}, {:key=>5, :value=>"Peter"}]
+          end
+        end
+        
+        xdescribe "breadth first search" do
+          it "will give an empty array for an empty tree" do
+            expect(tree.bfs).must_equal []
+          end
+          
+          it "will return an array of a level-by-level output of the tree" do
+            expect(tree_with_nodes.bfs).must_equal [{:key=>5, :value=>"Peter"}, {:key=>3, :value=>"Paul"}, 
+              {:key=>10, :value=>"Karla"}, {:key=>1, :value=>"Mary"}, 
+              {:key=>15, :value=>"Ada"}, {:key=>25, :value=>"Kari"}]
+            end
+          end
+          
+          describe "height" do 
+            it "will return 0 if tree is empty" do 
+              expect(tree.height()).must_equal 0
+            end
+            
+            it "will return the number of nodes in the longest path" do
+              expect(tree_with_nodes.height).must_equal 4
+              tree_with_nodes.add(60, "sam")
+              tree_with_nodes.add(58, "penny")
+              tree_with_nodes.add(65, "sam")
+              expect(tree_with_nodes.height).must_equal 6
+            end
+            
+            it "will give the correct height of a binary search tree" do
+              tree_with_nodes.add(30, "Tatiana")
+              expect(tree_with_nodes.height).must_equal 5
+            end
+          end
+          
+          describe "delete" do
+            it "can delete a node in the tree" do
+              # Arrange & Assert
+              expect(tree_with_nodes.find(15)).must_equal "Ada"
+              
+              # Act
+              tree_with_nodes.delete(15)
+              
+              # Assert
+              expect(tree_with_nodes.find(15)).must_be_nil
+            end
+            
+            it "will return nil if the node is not in the tree when it's deleted" do
+              # Arrange & Act
+              answer = tree_with_nodes.delete(47)
+              
+              # Assert
+              expect(answer).must_be_nil
+              expect(tree_with_nodes.find(47)).must_be_nil
+            end
+          end
+        end
+        
\ No newline at end of file