diff --git a/lib/reverse_sentence.rb b/lib/reverse_sentence.rb
index 3fe7cac..1ffad80 100644
--- a/lib/reverse_sentence.rb
+++ b/lib/reverse_sentence.rb
@@ -1,6 +1,48 @@
 # A method to reverse the words in a sentence, in place.
-# Time complexity: ?
-# Space complexity: ?
-def reverse_sentence(my_sentence)
-  raise NotImplementedError
+# Time complexity: O(N)
+# Space complexity: O(N)
+
+# reverse string given start and ending index
+def reverse_word(string, start, ending)
+  
+  i = start
+  j = ending
+  
+  while i < j
+    temp = string[i]
+    string[i] = string[j]
+    string[j] = temp
+    
+    i += 1
+    j -= 1
+  end
+end
+
+# call method made to reverse sentence
+
+def reverse_sentence(string)
+  if string == nil
+    return
+  end
+  reverse_word(string, 0, string.length - 1)
+  start = 0
+  while start < string.length
+    if string[start] == " "
+      start += 1 
+      next
+      
+    else # found the start of a word
+      ending = start
+      while ending <= string.length
+        if string[ending] == " " || ending == string.length
+          reverse_word(string, start, ending - 1)
+          start = ending
+          break
+        end
+        
+        ending += 1 
+        
+      end
+    end
+  end
 end
diff --git a/lib/sort_by_length.rb b/lib/sort_by_length.rb
index a5713ad..e7ee463 100644
--- a/lib/sort_by_length.rb
+++ b/lib/sort_by_length.rb
@@ -1,7 +1,27 @@
 # A method which will return an array of the words in the string
 #  sorted by the length of the word.
-# Time complexity: ?
-# Space complexity: ?
+# Time complexity: O(N^2)
+# Space complexity: O(N)
+
 def sort_by_length(my_sentence)
-  raise NotImplementedError, "Method not implemented"
+  sentence_array = my_sentence.split(" ")
+  bubble_sort(sentence_array, sentence_array.length)
+  return sentence_array
+end
+
+# cite: https://github.com/Ada-Developers-Academy/textbook-curriculum/blob/master/04-cs-fundamentals/classroom/Sorting.md
+def bubble_sort(array, length)
+  i = 0
+  while i < length - 1 # outer loop
+    j = 0
+    while j < length-i-1 # inner loop
+      if array[j].length > array[j+1].length # swap if length of word is greater than other
+        temp = array[j]
+        array[j] = array[j+1]
+        array[j+1] = temp
+      end
+      j += 1
+    end
+    i += 1
+  end
 end
diff --git a/test/sort_by_length.rb b/test/sort_by_length_test.rb
similarity index 100%
rename from test/sort_by_length.rb
rename to test/sort_by_length_test.rb