diff --git a/challenges/01-front-end-development-certification/advanced-bonfires.json b/challenges/01-front-end-development-certification/advanced-bonfires.json
index 7a098352be..d79b88d1c5 100644
--- a/challenges/01-front-end-development-certification/advanced-bonfires.json
+++ b/challenges/01-front-end-development-certification/advanced-bonfires.json
@@ -81,8 +81,8 @@
       "id": "a3f503de51cf954ede28891d",
       "title": "Symmetric Difference",
       "description": [
-        "Create a function that takes two or more arrays and returns an array of the symmetric difference of the provided arrays.",
-        "The mathematical term symmetric difference refers to the elements in two sets that are in either the first or second set, but not in both.",
+        "Create a function that takes two or more arrays and returns an array of the <dfn>symmetric difference</dfn> (<code>&xutri;</code> or <code>&oplus;</code>) of the provided arrays.",
+        "Given two sets (for example set <code>A = {1, 2, 3}</code> and set <code>B = {2, 3, 4}</code>), the mathematical term \"symmetric difference\" of two sets is the set of elements which are in either of the two sets, but not in both (<code>A &xutri; B = C = {1, 4}</code>). For every additional symmetric difference you take (say on a set <code>D = {2, 3}</code>), you should get the set with elements which are in either of the two the sets but not both (<code>C &xutri; D = {1, 4} &xutri; {2, 3} = {1, 2, 3, 4}</code>).",
         "Remember to use <a href='//github.com/FreeCodeCamp/freecodecamp/wiki/How-to-get-help-when-you-get-stuck' target='_blank'>Read-Search-Ask</a> if you get stuck. Try to pair program. Write your own code."
       ],
       "challengeSeed": [
@@ -225,8 +225,8 @@
       "id": "a7bf700cd123b9a54eef01d5",
       "title": "No repeats please",
       "description": [
-        "Return the number of total permutations of the provided string that don't have repeated consecutive letters.",
-        "For example, 'aab' should return 2 because it has 6 total permutations, but only 2 of them don't have the same letter (in this case 'a') repeating.",
+        "Return the number of total permutations of the provided string that don't have repeated consecutive letters. Assume that duplicate characters are each unique.",
+        "For example, <code>aab</code> should return 2 because it has 6 total permutations (<code>aab</code>, <code>aab</code>, <code>aba</code>, <code>aba</code>, <code>baa</code>, <code>baa</code>), but only 2 of them (<code>aba</code> and <code>aba</code>) don't have the same letter (in this case <code>a</code>) repeating.",
         "Remember to use <a href='//github.com/FreeCodeCamp/freecodecamp/wiki/How-to-get-help-when-you-get-stuck' target='_blank'>Read-Search-Ask</a> if you get stuck. Try to pair program. Write your own code."
       ],
       "challengeSeed": [
diff --git a/challenges/01-front-end-development-certification/bootstrap.json b/challenges/01-front-end-development-certification/bootstrap.json
index 098ebc5885..dd5fcf5942 100644
--- a/challenges/01-front-end-development-certification/bootstrap.json
+++ b/challenges/01-front-end-development-certification/bootstrap.json
@@ -950,7 +950,7 @@
       "id": "bad87fee1348bd9aede08845",
       "title": "Create a Custom Heading",
       "description": [
-        "We will make a simple heading for our Cat Photo App by putting them in the same row.",
+        "We will make a simple heading for our Cat Photo App by putting the title and relaxing cat image in the same row.",
         "Remember, Bootstrap uses a responsive grid system, which makes it easy to put elements into rows and specify each element's relative width. Most of Bootstrap's classes can be applied to a <code>div</code> element.",
         "Here's a diagram of how Bootstrap's 12-column grid layout works:",
         "<a href=\"http://i.imgur.com/FaYuui8.png\" data-lightbox=\"img-enlarge\"><img class=\"img-responsive\" src=\"http://i.imgur.com/FaYuui8.png\" title=\"Click to enlarge\" alt=\"an image illustrating Bootstrap's grid system\"></a>",
diff --git a/challenges/01-front-end-development-certification/intermediate-bonfires.json b/challenges/01-front-end-development-certification/intermediate-bonfires.json
index dfbe2a5233..d62675c923 100644
--- a/challenges/01-front-end-development-certification/intermediate-bonfires.json
+++ b/challenges/01-front-end-development-certification/intermediate-bonfires.json
@@ -48,7 +48,7 @@
       "id": "a5de63ebea8dbee56860f4f2",
       "title": "Diff Two Arrays",
       "description": [
-        "Compare two arrays and return a new array with any items only found in one of the original arrays.",
+        "Compare two arrays and return a new array with any items only found in one of the two given arrays, but not both. In other words, return the symmetric difference of the two arrays.",
         "Remember to use <a href='//github.com/FreeCodeCamp/freecodecamp/wiki/How-to-get-help-when-you-get-stuck' target='_blank'>Read-Search-Ask</a> if you get stuck. Try to pair program. Write your own code."
       ],
       "challengeSeed": [