diff --git a/lib/queue.rb b/lib/queue.rb
index 828217c6..7e1fd241 100644
--- a/lib/queue.rb
+++ b/lib/queue.rb
@@ -1,31 +1,56 @@
 class Queue
 
+    MAX_SIZE = 20
+
   def initialize
-    # @store = ...
-    raise NotImplementedError, "Not yet implemented"
+    @store = Array.new
+    @head = @tail = 0
   end
 
+  # add value to tail
   def enqueue(element)
-    raise NotImplementedError, "Not yet implemented"
+    # using mod to account for cicular increment 20 % 20 = 0
+    # check if queue is full
+    raise ArgumentError.new("Queue is full, cannot add element") if @head == (@tail + 1) % MAX_SIZE
+    # otherwise add element as tail value
+
+    @store[@tail] = element
+    @tail = (@tail + 1) % MAX_SIZE
+
+    return @store
   end
 
   def dequeue
-    raise NotImplementedError, "Not yet implemented"
+    raise ArgumentError.new("Queue is empty, cannot delete element") if @head == @tail
+
+    removed_element = @store[@head]
+    # @store[@head] = nil
+    # @store = @store.compact
+    @head = (@head + 1) % MAX_SIZE
+
+    return removed_element
   end
 
   def front
-    raise NotImplementedError, "Not yet implemented"
+    return @store[@head]
   end
 
   def size
-    raise NotImplementedError, "Not yet implemented"
+    return 0
   end
 
   def empty?
-    raise NotImplementedError, "Not yet implemented"
+    return @head == @tail
   end
 
   def to_s
+  # TODO: refactor dequeue to not have to have this conditional
+  # has to do with removing nil which affects the index. This is P2. P1: Graduate!
+  if @tail >= @head 
+    @store = @store[@head...@tail]
+  else
+    @store = @store[@head...MAX_SIZE] + (@store[0...@tail])
+  end
     return @store.to_s
   end
 end
diff --git a/lib/stack.rb b/lib/stack.rb
index cfc6ef0f..f83da154 100644
--- a/lib/stack.rb
+++ b/lib/stack.rb
@@ -1,19 +1,20 @@
 class Stack
   def initialize
-    # @store = ...
-    raise NotImplementedError, "Not yet implemented"
+    @store = LinkedList.new
   end
 
   def push(element)
-    raise NotImplementedError, "Not yet implemented"
+    @store.add_first(element)
   end
 
   def pop
-    raise NotImplementedError, "Not yet implemented"
+    return nil if self.empty?
+    element = @store.remove_first
+    return element
   end
 
   def empty?
-    raise NotImplementedError, "Not yet implemented"
+    return @store.empty?
   end
 
   def to_s