diff --git a/00_hello/hello.rb b/00_hello/hello.rb
new file mode 100644
index 000000000..3623e57f4
--- /dev/null
+++ b/00_hello/hello.rb
@@ -0,0 +1,7 @@
+def hello
+  "Hello!"
+end
+
+def greet(who)
+  "Hello, #{who}!"
+end
\ No newline at end of file
diff --git a/00_hello/hello_spec.rb b/00_hello/hello_spec.rb
index 26075944a..3eed35159 100644
--- a/00_hello/hello_spec.rb
+++ b/00_hello/hello_spec.rb
@@ -25,7 +25,7 @@
 # Open up `hello.rb` in a text editor. Save it. Run the test again.
 #
 #     rake
-#
+#ra
 # ## Watch it fail
 #
 # Now you should see an error like this:
diff --git a/01_temperature/temperature.rb b/01_temperature/temperature.rb
new file mode 100644
index 000000000..7e06948db
--- /dev/null
+++ b/01_temperature/temperature.rb
@@ -0,0 +1,7 @@
+def ftoc(f_temp)
+  c_temp = (f_temp - 32) * 5 / 9
+end
+
+def ctof(c_temp)
+  f_temp = c_temp.to_f * 9 / 5 + 32.0
+end
\ No newline at end of file
diff --git a/02_calculator/calculator.rb b/02_calculator/calculator.rb
new file mode 100644
index 000000000..fffb59dea
--- /dev/null
+++ b/02_calculator/calculator.rb
@@ -0,0 +1,17 @@
+def add(a, b)
+  a + b
+end
+
+def subtract(a, b)
+  a - b
+end
+
+def sum(arr)
+  sum = 0
+
+  arr.each do |i|
+    sum += i
+  end
+
+  sum
+end
\ No newline at end of file
diff --git a/03_simon_says/simon_says.rb b/03_simon_says/simon_says.rb
new file mode 100644
index 000000000..6005d2c7f
--- /dev/null
+++ b/03_simon_says/simon_says.rb
@@ -0,0 +1,57 @@
+def echo(s)
+  s
+end
+
+def shout(s)
+  s.upcase
+end
+
+def repeat(s, n_times = 2)
+  repeat_s = s
+  repeat_s += " #{s}" * (n_times - 1)
+end
+
+def start_of_word(word, characters)
+  partial_word = ""
+
+  characters.times do |c|
+    partial_word += word[c]
+  end
+
+  partial_word
+end
+
+def first_word(words)
+  first_word = ""
+
+  i = 0
+  until words[i] == " " do
+    first_word += words[i]
+    i += 1
+  end
+
+  first_word
+end
+
+
+def titleize(phrase)
+  word = ""
+  words = []
+
+  phrase.length.times do |i|
+    if phrase[i] == " "
+      words.push(word.downcase)
+      word = ""
+    else i == phrase.length - 1
+      word += phrase[i]
+    end
+    words.push(word.downcase) if i == phrase.length - 1
+  end
+
+  words.each_with_index do |word, i|
+    words[i][0] = word[0].upcase unless word == "the" || word == "and" || word == "over"
+    words[i][0] = word[0].upcase if i == 0
+  end
+
+  words = words.join(" ")
+end
diff --git a/04_pig_latin/pig_latin.rb b/04_pig_latin/pig_latin.rb
new file mode 100644
index 000000000..b98753d27
--- /dev/null
+++ b/04_pig_latin/pig_latin.rb
@@ -0,0 +1,26 @@
+def translate(phrase)
+  words = phrase.split(' ')
+
+  words.each_with_index do |word, i|
+    translated_word = word.downcase
+
+    case translated_word[0..2]
+      when /thr/, /sch/, /[^aeiou]qu/
+        translated_word += translated_word[0..2]
+        translated_word = translated_word[3..-1]
+      when /ch./, /qu./, /th./, /br./
+        translated_word += translated_word[0..1]
+        translated_word = translated_word[2..-1]
+      when /[^aeiou]../
+        translated_word += translated_word[0]
+        translated_word = translated_word[1..-1]
+      else
+
+    end
+
+    translated_word += "ay"
+    words[i] = translated_word
+  end
+
+  words = words.join(" ")
+end
\ No newline at end of file
diff --git a/05_silly_blocks/silly_blocks.rb b/05_silly_blocks/silly_blocks.rb
new file mode 100644
index 000000000..d64eb0547
--- /dev/null
+++ b/05_silly_blocks/silly_blocks.rb
@@ -0,0 +1,29 @@
+def word_reverse(string)
+  reverse_string = ""
+
+  i = -1
+  string.length.times do
+    reverse_string += string[i]
+    i -= 1
+  end
+
+  reverse_string
+end
+
+def reverser
+  text = yield.to_s.split
+
+  text.each_with_index do |word, i|
+    text[i] = word_reverse(word).downcase
+  end
+
+  text = text.join(" ")
+end
+
+def adder(n = 1)
+  yield + n
+end
+
+def repeater(n = 1)
+  n.times { yield }
+end
\ No newline at end of file
diff --git a/06_performance_monitor/performance_monitor.rb b/06_performance_monitor/performance_monitor.rb
new file mode 100644
index 000000000..659cd8072
--- /dev/null
+++ b/06_performance_monitor/performance_monitor.rb
@@ -0,0 +1,7 @@
+def measure(number_of_times = 1)
+  start = Time.now
+  number_of_times.times { yield }
+  finish = Time.now
+  duration = finish - start
+  average_duration = duration / number_of_times
+end
\ No newline at end of file
diff --git a/07_hello_friend/friend.rb b/07_hello_friend/friend.rb
new file mode 100644
index 000000000..e8e132afa
--- /dev/null
+++ b/07_hello_friend/friend.rb
@@ -0,0 +1,5 @@
+class Friend
+  def greeting(someone = false)
+    someone ? "Hello, #{someone}!" : "Hello!"
+  end
+end
\ No newline at end of file
diff --git a/08_book_titles/book.rb b/08_book_titles/book.rb
new file mode 100644
index 000000000..ef147f70e
--- /dev/null
+++ b/08_book_titles/book.rb
@@ -0,0 +1,44 @@
+class Book
+  def initialize
+    @title = ""
+  end
+
+  def title
+    @title
+  end
+
+  def title=(new_title)
+    @title = titleize(new_title)
+  end
+
+  def titleize(phrase)
+    word = ""
+    words = []
+
+    phrase.length.times do |i|
+      if phrase[i] == " "
+        words.push(word.downcase)
+        word = ""
+      else i == phrase.length - 1
+      word += phrase[i]
+      end
+      words.push(word.downcase) if i == phrase.length - 1
+    end
+
+    words.each_with_index do |word, i|
+      words[i][0] = word[0].upcase unless lowercase_word?(word)
+      words[i][0] = word[0].upcase if i == 0
+    end
+
+    words = words.join(" ")
+  end
+
+  def lowercase_word?(word)
+    lowercase_words = ["the", "and", "over", "under", "of", "in", "a", "an"]
+    lowercase_words.each do |lowercase_word|
+      return true if word.downcase == lowercase_word
+    end
+
+    return false
+  end
+end
\ No newline at end of file
diff --git a/09_timer/timer.rb b/09_timer/timer.rb
new file mode 100644
index 000000000..b9ef41807
--- /dev/null
+++ b/09_timer/timer.rb
@@ -0,0 +1,19 @@
+class Timer
+  def initialize
+    @seconds = 0
+  end
+
+  attr_accessor :seconds
+
+  def time_string
+    hours = @seconds / 60 / 60
+    minutes = (@seconds / 60) - (hours * 60)
+    seconds = @seconds - (hours * 60 * 60) - (minutes * 60)
+
+    hours_string = hours < 10 ? "0#{hours}" : hours.to_s
+    minutes_string = minutes < 10 ? "0#{minutes}" : minutes.to_s
+    seconds_string = seconds < 10 ? "0#{seconds}" : seconds.to_s
+
+    "#{hours_string}:#{minutes_string}:#{seconds_string}"
+  end
+end
diff --git a/10_temperature_object/temperature.rb b/10_temperature_object/temperature.rb
new file mode 100644
index 000000000..e3e3f93be
--- /dev/null
+++ b/10_temperature_object/temperature.rb
@@ -0,0 +1,41 @@
+class Temperature
+  def initialize(options)
+    @in_celsius = options[:c] ? options[:c] : ftoc(options[:f])
+    @in_fahrenheit = options[:f] ? options[:f] : ctof(options[:c])
+  end
+
+  attr_reader :in_celsius, :in_fahrenheit
+
+  def self.from_celsius(in_celsius)
+    Temperature.new( { c: in_celsius } )
+  end
+
+  def self.from_fahrenheit(in_fahrenheit)
+    Temperature.new( { f: in_fahrenheit } )
+  end
+
+  def ftoc(in_fahrenheit)
+    in_celsius = (in_fahrenheit - 32) * 5 / 9
+  end
+
+  def ctof(in_celsius)
+    in_fahrenheit = in_celsius.to_f * 9 / 5 + 32.0
+  end
+end
+
+class Celsius < Temperature
+  def initialize(in_celsius)
+    @in_celsius = in_celsius
+    @in_fahrenheit = ctof(in_celsius)
+  end
+end
+
+class Fahrenheit < Temperature
+  def initialize(in_fahrenheit)
+    @in_celsius = ftoc(in_fahrenheit)
+    @in_fahrenheit = in_fahrenheit
+  end
+end
+
+
+
diff --git a/11_dictionary/dictionary.rb b/11_dictionary/dictionary.rb
new file mode 100644
index 000000000..01adfa287
--- /dev/null
+++ b/11_dictionary/dictionary.rb
@@ -0,0 +1,49 @@
+class Dictionary
+  attr_reader :entries
+
+  def initialize
+    @entries = {}
+  end
+
+  def add(entry)
+    @entries[entry] = nil if entry.is_a?(String)
+
+    if entry.is_a?(Hash)
+      entry.each_key { |key| @entries[key.to_s] = entry[key].to_s }
+    end
+  end
+
+  def include?(keyword)
+    @entries.each_key do |entry_key|
+      return true if entry_key == keyword
+    end
+
+    return false
+  end
+
+  def find(keyword)
+    entry = {}
+
+    @entries.each_key do |key|
+      entry[key] = @entries[key] if key.include?(keyword)
+    end
+
+    return entry
+  end
+
+  def keywords
+    keywords = @entries.keys.to_a
+    keywords.sort
+  end
+
+  def printable
+    printable_text = []
+
+    keywords.each do |key|
+      printable_text.push("[#{key}] \"#{@entries[key]}\"")
+    end
+
+    return printable_text.join("\n")
+  end
+
+end
\ No newline at end of file
diff --git a/12_rpn_calculator/rpn_calculator.rb b/12_rpn_calculator/rpn_calculator.rb
new file mode 100644
index 000000000..241b3560b
--- /dev/null
+++ b/12_rpn_calculator/rpn_calculator.rb
@@ -0,0 +1,89 @@
+class RPNCalculator
+  attr_reader :value
+
+  def initialize
+    @stack = []
+  end
+
+  def push(val)
+    @stack.push(val)
+  end
+
+  def value
+    @stack[-1]
+  end
+
+  def plus
+    if @stack.count >= 2
+      b = @stack.pop
+      a = @stack.pop
+      push(a + b)
+    else
+      raise "calculator is empty"
+    end
+  end
+
+  def minus
+    if @stack.count >= 2
+      b = @stack.pop
+      a = @stack.pop
+      push(a - b)
+    else
+      raise "calculator is empty"
+    end
+  end
+
+  def divide
+    if @stack.count >= 2
+      b = @stack.pop.to_f
+      a = @stack.pop.to_f
+      push(a / b)
+    else
+      raise "calculator is empty"
+    end
+  end
+
+  def times
+    if @stack.count >= 2
+      b = @stack.pop
+      a = @stack.pop
+      push(a * b)
+    else
+      raise "calculator is empty"
+    end
+  end
+
+  def tokens(s)
+    tokenized_s = []
+
+    s.length.times do |i|
+      next if s[i] == " "
+      /[0-9]/.match(s[i]) ? tokenized_s.push(s[i].to_i) : tokenized_s.push(:"#{s[i]}")
+    end
+
+    return tokenized_s
+  end
+
+  def evaluate(s)
+    s.length.times do |i|
+      case s[i]
+        when /[0-9]/
+          push(s[i].to_i)
+        when "+"
+          plus
+        when "-"
+          minus
+        when "/"
+          divide
+        when "*"
+          times
+        else
+          next
+      end
+    end
+
+    value
+  end
+
+end
+
diff --git a/14_array_extensions/array_extensions.rb b/14_array_extensions/array_extensions.rb
new file mode 100644
index 000000000..e0e464c0f
--- /dev/null
+++ b/14_array_extensions/array_extensions.rb
@@ -0,0 +1,28 @@
+class Array
+  def sum
+    sum = 0
+    return sum unless self.count > 0
+
+    self.each { |i| sum += i }
+
+    return sum
+  end
+
+  def square
+    return [] unless self.count > 0
+
+    squared_arr = []
+    self.each { |i| squared_arr.push(i**2) }
+
+    return squared_arr
+  end
+
+  def square!
+    return self unless self.count > 0
+
+    self.each_with_index { |val, i| self[i] = val**2 }
+
+    return self
+  end
+
+end
\ No newline at end of file
diff --git a/15_in_words/in_words.rb b/15_in_words/in_words.rb
new file mode 100644
index 000000000..3ad770ff6
--- /dev/null
+++ b/15_in_words/in_words.rb
@@ -0,0 +1,61 @@
+class Fixnum
+  def in_words
+    numbers_in_words = {}
+    numbers_in_words[0] = 'zero'
+    numbers_in_words[1] = 'one'
+    numbers_in_words[2] = 'two'
+    numbers_in_words[3] = 'three'
+    numbers_in_words[4] = 'four'
+    numbers_in_words[5] = 'five'
+    numbers_in_words[6] = 'six'
+    numbers_in_words[7] = 'seven'
+    numbers_in_words[8] = 'eight'
+    numbers_in_words[9] = 'nine'
+    numbers_in_words[10] = 'ten'
+    numbers_in_words[11] = 'eleven'
+    numbers_in_words[12] = 'twelve'
+    numbers_in_words[13] = 'thirteen'
+    numbers_in_words[14] = 'fourteen'
+    numbers_in_words[15] = 'fifteen'
+    numbers_in_words[16] = 'sixteen'
+    numbers_in_words[17] = 'seventeen'
+    numbers_in_words[18] = 'eighteen'
+    numbers_in_words[19] = 'nineteen'
+    numbers_in_words[20] = 'twenty'
+    numbers_in_words[30] = 'thirty'
+    numbers_in_words[40] = 'forty'
+    numbers_in_words[50] = 'fifty'
+    numbers_in_words[60] = 'sixty'
+    numbers_in_words[70] = 'seventy'
+    numbers_in_words[80] = 'eighty'
+    numbers_in_words[90] = 'ninety'
+    numbers_in_words[100] = 'hundred'
+    numbers_in_words[1_000] = 'thousand'
+    numbers_in_words[1_000_000] = 'million'
+    numbers_in_words[1_000_000_000] = 'billion'
+    numbers_in_words[1_000_000_000_000] = 'trillion'
+
+    ones = self % 10
+    tens = self % 100 - ones
+    under_20 = self % 20
+    hundreds = self % 1_000 / 100
+    thousands = self % 1_000_000 / 1_000
+    millions = self % 1_000_000_000 / 1_000_000
+    billions = self % 1_000_000_000_000 / 1_000_000_000
+    trillions = self % 1_000_000_000_000_000 / 1_000_000_000_000
+
+    return numbers_in_words[self] if self < 20 && self >= 0
+    return numbers_in_words[self] if self < 100 && self % 10 == 0 && self > 0
+
+    words = []
+    words.push("#{trillions.in_words} trillion") if trillions > 0
+    words.push("#{billions.in_words} billion") if billions > 0
+    words.push("#{millions.in_words} million") if millions > 0
+    words.push("#{thousands.in_words} thousand") if thousands > 0
+    words.push("#{hundreds.in_words} hundred") if hundreds > 0
+    words.push("#{tens.in_words}") if tens >= 20
+    words.push("#{ones.in_words}") if tens >= 20 && ones > 0
+    words.push("#{under_20.in_words}") if tens < 20 && under_20 > 0
+    words.join(" ")
+  end
+end
\ No newline at end of file