diff --git a/lib/reverse_sentence.rb b/lib/reverse_sentence.rb
index 3fe7cac..72f5fc8 100644
--- a/lib/reverse_sentence.rb
+++ b/lib/reverse_sentence.rb
@@ -1,6 +1,19 @@
+
 # A method to reverse the words in a sentence, in place.
 # Time complexity: ?
 # Space complexity: ?
-def reverse_sentence(my_sentence)
-  raise NotImplementedError
+
+def reverse_sentence(test_string)
+  half = test_string.length / 2
+  # loop through elements n/2 times (ignores central element if length is odd)
+  half.times do |i|
+    # swap all characters/whitespace ("  Yoda" => "adoY  ")
+    test_string[i], test_string[-i-1] = test_string[-i-1], test_string[i]
+  end
+  
+  # can't figure out how to reverse letters in each word :(
+  
+  return test_string
 end
+
+# per Dianna, I can reverse words in a new array and then reassign values to original array. Does this count as modifying in place? 
\ No newline at end of file
diff --git a/lib/sort_by_length.rb b/lib/sort_by_length.rb
index a5713ad..d3c617b 100644
--- a/lib/sort_by_length.rb
+++ b/lib/sort_by_length.rb
@@ -1,7 +1,30 @@
 # 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: This is an insertion sort with two loops, so time complexity is O(n^2) / quadratic
+# Space complexity: O(1) / constant
+
 def sort_by_length(my_sentence)
-  raise NotImplementedError, "Method not implemented"
+  # split sentence into array of strings
+  my_sentence_words = my_sentence.split(" ") 
+  array_length = my_sentence_words.length
+  i = 1
+  # set condition for outer loop to run
+  while i < array_length
+    # declare value for word to be considered 
+    to_insert = my_sentence_words[i] 
+    j = i # j = 4
+    # set conditions for inner loop to run
+    while j > 0 && my_sentence_words[j-1].length > to_insert.length 
+      # if conditions evaluate true, move word at [j] down one position
+      my_sentence_words[j] = my_sentence_words[j-1] 
+      # decrement counter for inner loop
+      j -= 1 
+    end
+    # not 100 percent sure what this variable is doing but I know it's necessary
+    my_sentence_words[j] = to_insert 
+    # increment counter for outer loop
+    i += 1 
+  end
+  return my_sentence_words
 end
+