diff --git a/spec_helper.rb b/spec_helper.rb
index 2d5c93d..0f63c0c 100644
--- a/spec_helper.rb
+++ b/spec_helper.rb
@@ -2,4 +2,7 @@
   config.expect_with :rspec do |c|
     c.syntax = [:should, :expect]
   end
+  config.mock_with :rspec do |mocks|
+    mocks.syntax = :should
+  end
 end
\ No newline at end of file
diff --git a/week4/class_materials/odd_number.rb b/week4/class_materials/odd_number.rb
new file mode 100644
index 0000000..1c86876
--- /dev/null
+++ b/week4/class_materials/odd_number.rb
@@ -0,0 +1,18 @@
+class OddNumber
+	include Comparable
+	attr_accessor :value
+
+	def initialize value
+		@value = value
+	end
+
+	def succ
+		return OddNumber.new(@value + 1) if @value.even?
+		OddNumber.new(@value + 2)
+	end
+
+	def <=> other
+		@value <=> other.value
+	end
+end
+
diff --git a/week4/class_materials/resources.txt b/week4/class_materials/resources.txt
new file mode 100644
index 0000000..725756d
--- /dev/null
+++ b/week4/class_materials/resources.txt
@@ -0,0 +1,3 @@
+Blocks, Procs, Lambdas, and Closures: http://www.robertsosinski.com/2008/12/21/understanding-ruby-blocks-procs-and-lambdas/
+
+
diff --git a/week4/class_materials/timer.rb b/week4/class_materials/timer.rb
new file mode 100644
index 0000000..67b7681
--- /dev/null
+++ b/week4/class_materials/timer.rb
@@ -0,0 +1,8 @@
+class Timer
+	def self.time_code(n=1)
+		start_time = Time.now
+		n.times{yield}
+		end_time = Time.now
+		(end_time - start_time) / n.to_f
+	end
+end
\ No newline at end of file
diff --git a/week4/class_materials/timer_spec.rb b/week4/class_materials/timer_spec.rb
new file mode 100644
index 0000000..e7c83b7
--- /dev/null
+++ b/week4/class_materials/timer_spec.rb
@@ -0,0 +1,33 @@
+require_relative '../../spec_helper.rb'
+require "#{File.dirname(__FILE__)}/timer"
+
+describe Timer do
+
+	it "should report the time difference" do
+		Time.stub(:now).and_return(0,3)
+		time_difference = Timer.time_code do
+		end
+		time_difference.should be_within(0.1).of(3.0)
+	end
+
+	it "should run our code" do
+		flag = false
+		Timer.time_code do
+			flag = true
+		end
+		flag.should be_true
+	end
+
+	it "should run our code multiple times" do
+		counter = 0
+		result = Timer.time_code(17) {counter += 1}
+		counter.should equal 17
+	end
+
+	it "should give the average time" do
+		Time.stub(:now).and_return(0,10)
+		result = Timer.time_code(10) { }
+		result.should be_within(0.1).of(1)
+	end
+
+end
diff --git a/week4/class_materials/week4.key b/week4/class_materials/week4.key
new file mode 100644
index 0000000..ac3687b
Binary files /dev/null and b/week4/class_materials/week4.key differ
diff --git a/week4/class_materials/week4.pdf b/week4/class_materials/week4.pdf
new file mode 100644
index 0000000..30c75fa
Binary files /dev/null and b/week4/class_materials/week4.pdf differ
diff --git a/week4/exercises/monsters.rb b/week4/exercises/monsters.rb
new file mode 100644
index 0000000..e86bbf6
--- /dev/null
+++ b/week4/exercises/monsters.rb
@@ -0,0 +1,53 @@
+$monsters = []
+
+$monsters << {
+	:name => 'Zombie',
+	:nocturnal => false,
+	:dangers => ['bites', 'scratches'],
+	:vulnerabilities => ['fire', 'decapitation'],
+	:legs => 2
+}
+$monsters << {
+	:name => 'Mummy',
+	:nocturnal => false,
+	:dangers => ['bites', 'scratches', 'curses'],
+	:vulnerabilities => ['fire', 'decapitation', 'cats'],
+	:legs => 2
+}
+$monsters << {
+	:name => 'Vampire',
+	:nocturnal => true,
+	:dangers => ['bites', 'hypnosis'],
+	:vulnerabilities => ['wood', 'decapitation', 'crosses', 'holy_water', 'garlic', 'daylight'],
+	:legs => 2
+}
+$monsters << {
+	:name => 'Werewolf',
+	:nocturnal => true,
+	:dangers => ['bites', 'scratches'],
+	:vulnerabilities => ['silver'],
+	:legs => 4
+}
+$monsters << {
+	:name => 'Blob',
+	:nocturnal => false,
+	:dangers => ['suffocation'],
+	:vulnerabilities => ['CO2', 'ice', 'cold'],
+	:legs => 0
+}
+
+puts "How many monsters are nocturnal?"
+puts $monsters.count{|m| m[:nocturnal]}
+
+puts "What are the names of the monsters that are nocturnal?"
+puts $monsters.select{|m| m[:nocturnal]}.map{|m| m[:name]}
+
+puts "How many legs do all our monsters have?"
+puts $monsters.map{|m| m[:legs]}.inject(:+)
+
+puts "What are the 2 most common dangers and vulnerabilities of our monsters?"
+puts "2 most common dangers:"
+puts $monsters.map{|m| m[:dangers]}.flatten.inject(Hash.new(0)){|h,d| h[d] += 1; h}.sort_by{|k,v| v}[-2..-1].map{|a| a[0]}
+puts "2 most common vulnerabilities:"
+puts $monsters.map{|m| m[:vulnerabilities]}.flatten.inject(Hash.new(0)){|h,v| h[v] += 1; h}.sort_by{|k,v| v}[-2..-1].map{|a| a[0]}
+
diff --git a/week4/homework/questions.txt b/week4/homework/questions.txt
new file mode 100644
index 0000000..ffaf215
--- /dev/null
+++ b/week4/homework/questions.txt
@@ -0,0 +1,13 @@
+Please Read:
+Chapter 10 Basic Input and Output
+The Rake Gem: http://rake.rubyforge.org/
+
+1. How does Ruby read files?
+
+2. How would you output "Hello World!" to a file called my_output.txt?
+
+3. What is the Directory class and what is it used for?
+
+4. What is an IO object?
+
+5. What is rake and what is it used for? What is a rake task?
diff --git a/week4/homework/worker_spec.rb b/week4/homework/worker_spec.rb
new file mode 100644
index 0000000..993cd49
--- /dev/null
+++ b/week4/homework/worker_spec.rb
@@ -0,0 +1,37 @@
+require_relative '../../spec_helper.rb'
+require "#{File.dirname(__FILE__)}/worker"
+
+describe Worker do
+
+	it "executes a block and returns a string" do
+		result = Worker.work do
+			"hello"
+		end
+		result.should == "hello"
+	end
+
+	it "executes a block and returns a number" do
+		result = Worker.work do
+			3 + 4
+		end
+		result.should == 7
+	end
+
+	it "executes a block in the context of the calling method" do
+		n = 1
+		result = Worker.work do
+			n + 4
+		end
+		result.should == 5
+	end
+
+
+	it "executes a block 3 times and returns the result" do
+		n = 5
+		result = Worker.work(3) do
+			n += 1
+		end
+		result.should == 8
+	end
+
+end