diff --git a/lib/queue.rb b/lib/queue.rb
index 828217c6..38893c44 100644
--- a/lib/queue.rb
+++ b/lib/queue.rb
@@ -1,16 +1,49 @@
 class Queue
 
   def initialize
-    # @store = ...
-    raise NotImplementedError, "Not yet implemented"
+    # first in, first out, like a check-out line
+    @store = Array.new(19)
+    # pointers to @store nodes
+    @front = @back = -1
   end
 
   def enqueue(element)
-    raise NotImplementedError, "Not yet implemented"
+    # if empty then add element node to index 0 
+    if @front == -1 && @back == -1
+      puts "setting front and back to 0"
+      @front = 0
+      @back = 0
+    end
+    # if queue is full
+    if @front == @back && !@store[@front].nil?
+      puts "adding #{element}, queue will be full"
+      puts "(@front: #{@front}, @back: #{@back}"
+    end
+    puts "adding #{element} to @back located at index #{@back}"
+    puts "@front: #{@front}"
+    @store[@back] = element
+    @back = (@back + 1) % @store.length
+    puts "moved @back to #{@back}"
+    return element
   end
 
   def dequeue
-    raise NotImplementedError, "Not yet implemented"
+    # if empty return nil
+    if @front == -1 && @back == -1
+      return nil
+    end
+    # if queue is not empty return the first element in the list (at front)
+    # and remove it from queue
+    dequeued = @store[@front]
+    @store[@front] = nil
+    @front = (@front + 1) % @store.length
+    # if it was the last one, set front and back to -1
+    if @front == @back && @store[@back].nil?
+      puts "it was the last one, resetting queue"
+      @front = @back = -1
+    end
+    puts "removed #{dequeued} from queue, @front: #{@front}, @back: #{@back}"
+    return dequeued
   end
 
   def front
@@ -18,14 +51,33 @@ def front
   end
 
   def size
-    raise NotImplementedError, "Not yet implemented"
+    # from front to end
+    if @front < @back
+      size = @store[@front...@back].length
+    # from back to end, then start to front
+    else
+      size = @store[@back..-1] + @store[0...@front]
+    end
+    return size
   end
 
   def empty?
-    raise NotImplementedError, "Not yet implemented"
+    return @front == @back && @back == -1
   end
 
   def to_s
-    return @store.to_s
+    # from front to end
+    if @front < @back
+      print_store = @store[@front...@back]
+    # from front to end, then 0 to back
+    else
+      print_store = @store[@front..-1] + @store[0...@back]
+    end
+    puts "front and back:"
+    puts @front
+    puts @back
+    puts "actual @store:"
+    puts @store.to_s
+    return print_store.to_s
   end
 end
diff --git a/lib/stack.rb b/lib/stack.rb
index cfc6ef0f..71dea12d 100644
--- a/lib/stack.rb
+++ b/lib/stack.rb
@@ -1,19 +1,21 @@
+require 'linked_list'
 class Stack
+  # first in, last out, like a pile of books
   def initialize
-    # @store = ...
-    raise NotImplementedError, "Not yet implemented"
+    @store = LinkedList.new
   end
 
   def push(element)
-    raise NotImplementedError, "Not yet implemented"
+    @store.add_last(element)
+    return @store
   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 8a7dcd9c..2781631d 100644
--- a/test/queue_test.rb
+++ b/test/queue_test.rb
@@ -11,14 +11,12 @@
   end
 
   it "adds something to an empty Queue" do
-    skip
     q = Queue.new
     q.enqueue(10)
     q.to_s.must_equal "[10]"
   end
 
   it "adds multiple somethings to a Queue" do
-    skip
     q = Queue.new
     q.enqueue(10)
     q.enqueue(20)
@@ -27,13 +25,36 @@
   end
 
   it "starts the size of a Queue at 0" do
-    skip
     q = Queue.new
     q.empty?.must_equal true
   end
 
+  it "calculates size correctly" do
+    q = Queue.new
+    q.enqueue(10)
+    q.enqueue(20)
+    q.enqueue(30)
+    expect(q.size).must_equal 3
+    q.dequeue
+    expect(q.size).must_equal 2  
+    q.enqueue(40)
+    q.enqueue(50)
+    q.enqueue(60)
+    q.enqueue(70)
+    q.enqueue(80)
+    q.enqueue(90)
+    q.enqueue(100)
+    q.enqueue(110)
+    q.enqueue(120)
+    expect(q.size).must_equal 11
+    q.dequeue
+    q.dequeue
+    q.dequeue
+    q.dequeue
+    expect(q.size).must_equal 7
+  end
+
   it "removes something from the Queue" do
-    skip
     q = Queue.new
     q.enqueue(5)
     removed = q.dequeue
@@ -42,7 +63,6 @@
   end
 
   it "removes the right something (LIFO)" do
-    skip
     q = Queue.new
     q.enqueue(5)
     q.enqueue(3)
@@ -53,7 +73,6 @@
   end
 
   it "properly adjusts the size with enqueueing and dequeueing" do
-    skip
     q = Queue.new
     q.empty?.must_equal true
     q.enqueue(-1)
@@ -65,7 +84,6 @@
   end
 
   it "returns the front element in the Queue" do
-    skip
     q = Queue.new
     q.enqueue(40)
     q.enqueue(22)
@@ -92,7 +110,6 @@
     q.enqueue(130)
     q.enqueue(140)
     q.enqueue(150)
-    q.enqueue(150)
     q.enqueue(160)
     q.enqueue(170)
     q.enqueue(180)
@@ -101,6 +118,6 @@
     q.enqueue(210)
     q.dequeue
 
-    expect(q.to_s).must_equal('[40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210, 220, 230, 240]')
+    expect(q.to_s).must_equal('[40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210]')
   end
 end
diff --git a/test/stack_test.rb b/test/stack_test.rb
index df5046c8..2cf9d5d9 100644
--- a/test/stack_test.rb
+++ b/test/stack_test.rb
@@ -10,14 +10,12 @@
   end
 
   it "pushes something onto a empty Stack" do
-    skip
     s = Stack.new
     s.push(10)
     s.to_s.must_equal "[10]"
   end
 
   it "pushes multiple somethings onto a Stack" do
-    skip
     s = Stack.new
     s.push(10)
     s.push(20)
@@ -26,13 +24,11 @@
   end
 
   it "starts the stack empty" do
-    skip
     s = Stack.new
     s.empty?.must_equal true
   end
 
   it "removes something from the stack" do
-    skip
     s = Stack.new
     s.push(5)
     removed = s.pop
@@ -41,7 +37,6 @@
   end
 
   it "removes the right something (LIFO)" do
-    skip
     s = Stack.new
     s.push(5)
     s.push(3)