diff --git a/binary_search_tree/tree.py b/binary_search_tree/tree.py
index cdd5abc..3ac9341 100644
--- a/binary_search_tree/tree.py
+++ b/binary_search_tree/tree.py
@@ -1,3 +1,7 @@
+from multiprocessing.dummy import current_process
+from typing import ItemsView
+
+
 class TreeNode:
     def __init__(self, key, val = None):
         if val == None:
@@ -9,50 +13,144 @@ def __init__(self, key, val = None):
         self.right = None
         
 
-
 class Tree:
     def __init__(self):
         self.root = None
 
-    # Time Complexity: 
-    # Space Complexity: 
+    # Time Complexity: 0(log n)
+    # Space Complexity: 0(log n) 
+    def add_helper(self, current_node, key, value):
+        # helper takes advantage of recursive
+        # if node is empty, return new node with key and value
+        if current_node == None:
+            return TreeNode(key, value)
+        if key <= current_node.key:
+            current_node.left = self.add_helper(current_node.left, key, value)
+        else:
+            current_node.right = self.add_helper(current_node.right, key, value) 
+        return current_node
+            
     def add(self, key, value = None):
-        pass
+        if self.root == None:
+            self.root = TreeNode(key, value)
+        else:
+            self.add_helper(self.root, key, value)
+            
 
-    # Time Complexity: 
-    # Space Complexity: 
+    # Time Complexity: 0(log n)
+    # Space Complexity: 0(log n)
     def find(self, key):
-        pass
+        if self.root == None:
+            return None
+        current = self.root
+        while current != None:
+            if current.key == key:
+                return current.value
+            elif current.key <key:
+                current = current.right
+            else:
+                current = current.left
+        return None
+
 
-    # Time Complexity: 
-    # Space Complexity: 
+    # Time Complexity: 0(n)
+    # Space Complexity: 0(n)
+    def inorder_helper(self, current_node, items):
+        if current_node != None:
+            self.inorder_helper(current_node.left, items)
+            items.append({"key": current_node.key, "value": current_node.value})
+            self.inorder_helper(current_node.right, items)
+        
     def inorder(self):
-        pass
+        #list of items to be returned --> depth-first traversal sorted key values in an ascending order, Left,Current,Right
+        items = []
+        self.inorder_helper(self.root, items)
+        return items
+
 
-    # Time Complexity: 
-    # Space Complexity:     
+    # Time Complexity: 0(n)
+    # Space Complexity: 0(n)   
+    def preorder_helper(self, current_node, items):
+        if current_node == None:
+            return items
+        else:
+            items.append({"key": current_node.key, "value": current_node.value})
+            self.preorder_helper(current_node.left, items)
+            self.preorder_helper(current_node.right, items)
+            return items
+     
     def preorder(self):
-        pass
+        #list of items to be returned --> depth-first traversal sorted current, left, right
+        items = []
+        if self.root:
+            self.preorder_helper(self.root, items)
+        return items
+
+
+    # Time Complexity: 0(n)
+    # Space Complexity: 0(n)  
+    def postorder_helper(self, current_node, items): 
+        if current_node:
+            self.postorder_helper(current_node.left, items)
+            self.postorder_helper(current_node.right, items)
+            items.append({"key": current_node.key, "value": current_node.value})
+        return items
+      
+    def postorder(self): 
+        #list of items to be returned --> depth-first traversal sorted left, right, current
+        items = []
+        if self.root:
+            self.postorder_helper(self.root, items)
+        return items
 
-    # Time Complexity: 
-    # Space Complexity:     
-    def postorder(self):
-        pass
 
-    # Time Complexity: 
-    # Space Complexity:     
+    # Time Complexity: 0(n)
+    # Space Complexity: 0(n)  
+    def height_helper(self, current_node):
+        # uses stack and recursion for each node in tree 
+        # plus one for the root node / the current node
+        if current_node != None:
+            height_left = self.height_helper(current_node.left)
+            height_right = self.height_helper(current_node.right)
+            return (max(height_left, height_right) + 1)
+        
+        else:
+            return 0
+         
     def height(self):
-        pass
+        return self.height_helper(self.root)
+
 
 
 #   # Optional Method
-#   # Time Complexity: 
-#   # Space Complexity: 
-    def bfs(self):
-        pass
+#   # Time Complexity: O(n)
+#   # Space Complexity: O(n)
 
+    def bfs_helper(self, current_node, sub_list):
+        if current_node.left:
+            sub_list.append(current_node.left)
+        if current_node.right:
+            sub_list.append(current_node.right)
         
-
+    
+    def bfs(self):
+        # uses queues to create sublists for each level, pops off elements from queue from left to right until sublist is empty to creates list, then adds children of each element to queue as popping off, repeats,
+        # recursion for each level
+        items = []
+        sub_list = []
+        
+        if not self.root:
+            return items
+        
+        items.append({"key": self.root.key, "value": self.root.value})
+        self.bfs_helper(self.root, sub_list)
+        
+        while sub_list:
+            current_node = sub_list.pop(0)
+            items.append({"key": current_node.key, "value": current_node.value})
+            self.bfs_helper(current_node, sub_list)
+        return items
+    
 
 #   # Useful for printing
     def to_s(self):