diff --git a/lib/linked_list.rb b/lib/linked_list.rb
index 136d8ac9..3d060b1d 100644
--- a/lib/linked_list.rb
+++ b/lib/linked_list.rb
@@ -37,7 +37,7 @@ def remove_first()
 
       value = @head.data
       @head = @head.next
-      @head.previous = nil
+      # @head.previous = nil
       return value
     end
 
diff --git a/lib/problems.rb b/lib/problems.rb
index 5085953d..e26f8a88 100644
--- a/lib/problems.rb
+++ b/lib/problems.rb
@@ -1,3 +1,4 @@
+# Wave 3
 require_relative './stack.rb'
 
 # Time Complexity: ?
@@ -6,6 +7,7 @@ def balanced(string)
   raise NotImplementedError, "Not implemented yet"
 end
 
+# Wave 4
 # Time Complexity: ?
 # Space Complexity: ?
 def evaluate_postfix(postfix_expression)
diff --git a/lib/queue.rb b/lib/queue.rb
index 828217c6..c553d8f5 100644
--- a/lib/queue.rb
+++ b/lib/queue.rb
@@ -1,28 +1,61 @@
+# Wave 2
+# require_relative './stack.rb'
+require "./linked_list"
+
 class Queue
 
   def initialize
-    # @store = ...
-    raise NotImplementedError, "Not yet implemented"
+    @store = LinkedList.new
+    @front = @back = -1
+# @front = -1
+# @back = -1
   end
 
   def enqueue(element)
-    raise NotImplementedError, "Not yet implemented"
+    if @front == -1 && @back == -1
+      @front = 0
+      @back = 1
+    end
+
+    if @front == @back
+      raise ArgumentError.new("Error")
+    end
+
+    return @store.add_last(element)
+
   end
 
   def dequeue
-    raise NotImplementedError, "Not yet implemented"
+    # if @front == -1 && @back == -1
+    #   @front = 0
+    #   @back = 1
+    # end
+ 
+    if @store.length > 0
+      return @store.remove_first()
+    end
+ 
+    # puts @store
+    # puts @front
+    # puts @back
+
   end
 
   def front
-    raise NotImplementedError, "Not yet implemented"
+    # raise NotImplementedError, "Not yet implemented"
+    return @store.get_first()
   end
 
   def size
-    raise NotImplementedError, "Not yet implemented"
+    # raise NotImplementedError, "Not yet implemented"
+    return @store.length
   end
 
   def empty?
-    raise NotImplementedError, "Not yet implemented"
+    # raise NotImplementedError, "Not yet implemented"
+    # return true if @front == @back
+    return @store.empty?
+
   end
 
   def to_s
diff --git a/lib/stack.rb b/lib/stack.rb
index cfc6ef0f..8beca9f4 100644
--- a/lib/stack.rb
+++ b/lib/stack.rb
@@ -1,19 +1,21 @@
+# wave 1
+require "./linked_list"
+
 class Stack
   def initialize
-    # @store = ...
-    raise NotImplementedError, "Not yet implemented"
+    @store = LinkedList.new
   end
 
   def push(element)
-    raise NotImplementedError, "Not yet implemented"
+    return @store.add_last(element)
   end
 
   def pop
-    raise NotImplementedError, "Not yet implemented"
+    return @store.remove_last()
   end
 
   def empty?
-    raise NotImplementedError, "Not yet implemented"
+    return @store.empty?
   end
 
   def to_s
diff --git a/test/queue_test.rb b/test/queue_test.rb
index 66372e26..e4ccf65d 100644
--- a/test/queue_test.rb
+++ b/test/queue_test.rb
@@ -11,14 +11,14 @@
   end
 
   it "adds something to an empty Queue" do
-    skip
+    # skip
     q = Queue.new
     q.enqueue(10)
     expect(q.to_s).must_equal "[10]"
   end
 
   it "adds multiple somethings to a Queue" do
-    skip
+    # skip
     q = Queue.new
     q.enqueue(10)
     q.enqueue(20)
@@ -27,13 +27,13 @@
   end
 
   it "starts the size of a Queue at 0" do
-    skip
+    # skip
     q = Queue.new
     q.empty?.must_equal true
   end
 
   it "a Queue is empty after removing all the elements" do
-    skip
+    # skip
     q = Queue.new
     q.enqueue(5)
     q.enqueue(6)
@@ -43,7 +43,7 @@
   end
 
   it "removes something from the Queue" do
-    skip
+    # skip
     q = Queue.new
     q.enqueue(5)
     removed = q.dequeue
@@ -52,18 +52,20 @@
   end
 
   it "removes the right something (LIFO)" do
-    skip
+    # skip
     q = Queue.new
     q.enqueue(5)
     q.enqueue(3)
     q.enqueue(7)
+    puts q
     removed = q.dequeue
+    puts q
     removed.must_equal 5
     q.to_s.must_equal "[3, 7]"
   end
 
   it "properly adjusts the size with enqueueing and dequeueing" do
-    skip
+    # skip
     q = Queue.new
     q.empty?.must_equal true
     q.enqueue(-1)
@@ -75,7 +77,7 @@
   end
 
   it "returns the front element in the Queue" do
-    skip
+    # skip
     q = Queue.new
     q.enqueue(40)
     q.enqueue(22)
@@ -84,6 +86,7 @@
     expect(q.dequeue).must_equal 22
   end
   it "works for a large Queue" do
+    # skip
     q = Queue.new
     q.enqueue(10)
     q.enqueue(20)
@@ -111,6 +114,6 @@
     q.enqueue(210)
     q.dequeue
 
-    expect(q.to_s).must_equal('[30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200]')
+    expect(q.to_s).must_equal('[40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 150, 160, 170, 180, 190, 200, 210]')
   end
 end
diff --git a/test/stack_test.rb b/test/stack_test.rb
index df5046c8..4c9118ac 100644
--- a/test/stack_test.rb
+++ b/test/stack_test.rb
@@ -10,14 +10,14 @@
   end
 
   it "pushes something onto a empty Stack" do
-    skip
+    # skip
     s = Stack.new
     s.push(10)
     s.to_s.must_equal "[10]"
   end
 
   it "pushes multiple somethings onto a Stack" do
-    skip
+    # skip
     s = Stack.new
     s.push(10)
     s.push(20)
@@ -26,13 +26,13 @@
   end
 
   it "starts the stack empty" do
-    skip
+    # skip
     s = Stack.new
     s.empty?.must_equal true
   end
 
   it "removes something from the stack" do
-    skip
+    # skip
     s = Stack.new
     s.push(5)
     removed = s.pop
@@ -41,7 +41,7 @@
   end
 
   it "removes the right something (LIFO)" do
-    skip
+    # skip
     s = Stack.new
     s.push(5)
     s.push(3)