diff --git a/config.json b/config.json
index 755371b4..e13c6805 100644
--- a/config.json
+++ b/config.json
@@ -1,10 +1,15 @@
 {
+  "language": "Racket",
   "active": true,
+  "blurb": "",
   "exercises": [
     {
+      "slug": "hello-world",
+      "uuid": "4fb471fc-4e6d-486d-abf5-939e89f028fc",
       "core": false,
+      "auto_approve": true,
+      "unlocked_by": null,
       "difficulty": 1,
-      "slug": "hello-world",
       "topics": [
         "string"
       ],
@@ -23,199 +28,209 @@
       "uuid": "27ffc2d2-e950-40a1-90fa-a1f3eec4fd36"
     },
     {
-      "core": false,
-      "difficulty": 1,
       "slug": "grains",
-      "topics": null,
+      "uuid": "b5b537d0-7c5d-45e5-af1d-b4da4f32514b",
+      "core": false,
       "unlocked_by": null,
-      "uuid": "b5b537d0-7c5d-45e5-af1d-b4da4f32514b"
+      "difficulty": 1,
+      "topics": null
     },
     {
-      "core": false,
-      "difficulty": 1,
       "slug": "leap",
-      "topics": null,
+      "uuid": "e84ac1ee-6e7e-40b4-826a-ed3d41890b83",
+      "core": false,
       "unlocked_by": null,
-      "uuid": "e84ac1ee-6e7e-40b4-826a-ed3d41890b83"
+      "difficulty": 1,
+      "topics": null
     },
     {
-      "core": false,
-      "difficulty": 1,
       "slug": "difference-of-squares",
-      "topics": null,
+      "uuid": "a3d9a2bb-a80a-487f-b529-64e20f7cf9b5",
+      "core": false,
       "unlocked_by": null,
-      "uuid": "a3d9a2bb-a80a-487f-b529-64e20f7cf9b5"
+      "difficulty": 1,
+      "topics": [
+        "math"
+      ]
     },
     {
-      "core": false,
-      "difficulty": 1,
       "slug": "perfect-numbers",
-      "topics": null,
+      "uuid": "72b2c36b-fcd5-4c8c-89e7-98bf24faaa3e",
+      "core": false,
       "unlocked_by": null,
-      "uuid": "72b2c36b-fcd5-4c8c-89e7-98bf24faaa3e"
+      "difficulty": 1,
+      "topics": [
+        "math"
+      ]
     },
     {
-      "core": false,
-      "difficulty": 1,
       "slug": "gigasecond",
-      "topics": null,
+      "uuid": "c7550977-bc29-47e9-9aeb-9e3ee34032b2",
+      "core": false,
       "unlocked_by": null,
-      "uuid": "c7550977-bc29-47e9-9aeb-9e3ee34032b2"
+      "difficulty": 1,
+      "topics": null
     },
     {
-      "core": false,
-      "difficulty": 1,
       "slug": "bob",
-      "topics": null,
+      "uuid": "3e5e67fa-991b-4120-abf0-6f10f9dfaca8",
+      "core": false,
       "unlocked_by": null,
-      "uuid": "3e5e67fa-991b-4120-abf0-6f10f9dfaca8"
+      "difficulty": 1,
+      "topics": null
     },
     {
-      "core": false,
-      "difficulty": 1,
       "slug": "collatz-conjecture",
-      "topics": null,
+      "uuid": "28102e69-dad0-4f3c-8cdf-5a18a73178a4",
+      "core": false,
       "unlocked_by": null,
-      "uuid": "28102e69-dad0-4f3c-8cdf-5a18a73178a4"
+      "difficulty": 1,
+      "topics": [
+        "math"
+      ]
     },
     {
-      "core": false,
-      "difficulty": 1,
       "slug": "hamming",
-      "topics": null,
+      "uuid": "f0a6e55d-6702-4043-bdcf-2ed99bf60645",
+      "core": false,
       "unlocked_by": null,
-      "uuid": "f0a6e55d-6702-4043-bdcf-2ed99bf60645"
+      "difficulty": 1,
+      "topics": null
     },
     {
-      "core": false,
-      "difficulty": 1,
       "slug": "scrabble-score",
-      "topics": null,
+      "uuid": "74d67f30-1f31-4289-a9bc-1bf69ec54ae2",
+      "core": false,
       "unlocked_by": null,
-      "uuid": "74d67f30-1f31-4289-a9bc-1bf69ec54ae2"
+      "difficulty": 1,
+      "topics": null
     },
     {
-      "core": false,
-      "difficulty": 1,
       "slug": "roman-numerals",
-      "topics": null,
+      "uuid": "c5a747dc-f283-4cf6-8435-fde885f63089",
+      "core": false,
       "unlocked_by": null,
-      "uuid": "c5a747dc-f283-4cf6-8435-fde885f63089"
+      "difficulty": 1,
+      "topics": null
     },
     {
+      "slug": "meetup",
+      "uuid": "72ac5f36-ec1b-465e-b359-1cc49efc262d",
       "core": false,
+      "unlocked_by": null,
       "difficulty": 1,
-      "slug": "meetup",
       "topics": [
         "conditionals",
         "dates",
         "parsing",
         "pattern_recognition",
         "strings"
-      ],
-      "unlocked_by": null,
-      "uuid": "72ac5f36-ec1b-465e-b359-1cc49efc262d"
+      ]
     },
     {
-      "core": false,
-      "difficulty": 1,
       "slug": "anagram",
-      "topics": null,
+      "uuid": "67b41645-7a02-4c45-af55-86401db69eee",
+      "core": false,
       "unlocked_by": null,
-      "uuid": "67b41645-7a02-4c45-af55-86401db69eee"
+      "difficulty": 1,
+      "topics": null
     },
     {
-      "core": false,
-      "difficulty": 1,
       "slug": "rna-transcription",
-      "topics": null,
+      "uuid": "2936d930-2359-44ea-8342-656016d3ec79",
+      "core": false,
       "unlocked_by": null,
-      "uuid": "2936d930-2359-44ea-8342-656016d3ec79"
+      "difficulty": 1,
+      "topics": null
     },
     {
-      "core": false,
-      "difficulty": 1,
       "slug": "etl",
-      "topics": null,
+      "uuid": "7c1cdc16-30c8-460f-aa6a-cc0655436f22",
+      "core": false,
       "unlocked_by": null,
-      "uuid": "7c1cdc16-30c8-460f-aa6a-cc0655436f22"
+      "difficulty": 1,
+      "topics": null
     },
     {
-      "core": false,
-      "difficulty": 1,
       "slug": "word-count",
-      "topics": null,
+      "uuid": "b931f727-b5b1-4f42-9799-faca692dd32e",
+      "core": false,
       "unlocked_by": null,
-      "uuid": "b931f727-b5b1-4f42-9799-faca692dd32e"
+      "difficulty": 1,
+      "topics": null
     },
     {
-      "core": false,
-      "difficulty": 1,
       "slug": "phone-number",
-      "topics": null,
+      "uuid": "aad41852-c939-4168-89c8-ae873892c5f9",
+      "core": false,
       "unlocked_by": null,
-      "uuid": "aad41852-c939-4168-89c8-ae873892c5f9"
+      "difficulty": 1,
+      "topics": null
     },
     {
-      "core": false,
-      "difficulty": 1,
       "slug": "nucleotide-count",
-      "topics": null,
+      "uuid": "9fbd3939-f71a-4506-bcc3-e9940d4027ed",
+      "core": false,
       "unlocked_by": null,
-      "uuid": "9fbd3939-f71a-4506-bcc3-e9940d4027ed"
+      "difficulty": 1,
+      "topics": null
     },
     {
-      "core": false,
-      "difficulty": 1,
       "slug": "raindrops",
-      "topics": null,
+      "uuid": "9795a374-30ae-492b-bcd7-1648ea5264b7",
+      "core": false,
       "unlocked_by": null,
-      "uuid": "9795a374-30ae-492b-bcd7-1648ea5264b7"
+      "difficulty": 1,
+      "topics": null
     },
     {
-      "core": false,
-      "difficulty": 1,
       "slug": "grep",
-      "topics": null,
+      "uuid": "37ab62d8-deb3-4fa4-8016-0b22f3d2f66d",
+      "core": false,
       "unlocked_by": null,
-      "uuid": "37ab62d8-deb3-4fa4-8016-0b22f3d2f66d"
+      "difficulty": 1,
+      "topics": null
     },
     {
-      "core": false,
-      "difficulty": 1,
       "slug": "say",
-      "topics": null,
+      "uuid": "0f64407b-0f01-4c4c-b721-fefdb8f98d16",
+      "core": false,
       "unlocked_by": null,
-      "uuid": "0f64407b-0f01-4c4c-b721-fefdb8f98d16"
+      "difficulty": 1,
+      "topics": null
     },
     {
-      "core": false,
-      "difficulty": 1,
       "slug": "allergies",
-      "topics": null,
+      "uuid": "881f83d7-1c80-4045-9a3f-def45c8f5764",
+      "core": false,
       "unlocked_by": null,
-      "uuid": "881f83d7-1c80-4045-9a3f-def45c8f5764"
+      "difficulty": 1,
+      "topics": null
     },
     {
-      "core": false,
-      "difficulty": 1,
       "slug": "list-ops",
-      "topics": null,
+      "uuid": "874b53f5-d9ef-4fd9-be62-3fe16692e565",
+      "core": false,
       "unlocked_by": null,
-      "uuid": "874b53f5-d9ef-4fd9-be62-3fe16692e565"
+      "difficulty": 1,
+      "topics": null
     },
     {
-      "core": false,
-      "difficulty": 1,
       "slug": "acronym",
-      "topics": null,
+      "uuid": "daeb92dc-efea-4bea-b657-3383b1880e49",
+      "core": false,
       "unlocked_by": null,
-      "uuid": "daeb92dc-efea-4bea-b657-3383b1880e49"
+      "difficulty": 1,
+      "topics": null
     },
     {
-      "deprecated": true,
       "slug": "accumulate",
-      "uuid": "b234225c-fcde-445f-9222-f80c25d0f499"
+      "uuid": "b234225c-fcde-445f-9222-f80c25d0f499",
+      "core": false,
+      "unlocked_by": null,
+      "difficulty": 0,
+      "topics": null,
+      "deprecated": true
     }
   ],
   "foregone": [],
diff --git a/config/maintainers.json b/config/maintainers.json
index a219a669..d3ac57b5 100644
--- a/config/maintainers.json
+++ b/config/maintainers.json
@@ -2,34 +2,34 @@
   "docs_url": "https://github.com/exercism/docs/blob/master/maintaining-a-track/maintainer-configuration.md",
   "maintainers": [
     {
-      "alumnus": false,
-      "avatar_url": null,
-      "bio": null,
       "github_username": "zenspider",
+      "alumnus": false,
+      "show_on_website": false,
+      "name": null,
       "link_text": null,
       "link_url": null,
-      "name": null,
-      "show_on_website": false
+      "avatar_url": null,
+      "bio": null
     },
     {
-      "alumnus": false,
-      "avatar_url": null,
-      "bio": null,
       "github_username": "arguello",
+      "alumnus": false,
+      "show_on_website": false,
+      "name": null,
       "link_text": null,
       "link_url": null,
-      "name": null,
-      "show_on_website": false
+      "avatar_url": null,
+      "bio": null
     },
     {
-      "alumnus": false,
-      "avatar_url": null,
-      "bio": null,
       "github_username": "yurrriq",
+      "alumnus": false,
+      "show_on_website": false,
+      "name": null,
       "link_text": null,
       "link_url": null,
-      "name": null,
-      "show_on_website": false
+      "avatar_url": null,
+      "bio": null
     }
   ]
-}
\ No newline at end of file
+}
diff --git a/docs/LEARNING.md b/docs/LEARNING.md
index 82dae602..124b42a4 100644
--- a/docs/LEARNING.md
+++ b/docs/LEARNING.md
@@ -5,4 +5,4 @@ These resources can help you get started:
 * [Continue: Web Applications in Racket](http://docs.racket-lang.org/continue/index.html)
 * [More: Systems Programming with Racket](http://docs.racket-lang.org/more/index.html)
 * [How to Design Programs](http://htdp.org/), by Matthias Felleisen, Robert Bruce Findler, Matthew Flatt, and Shiriam Krishnamurthi
-* [The Little Schemer](http://mitpress.mit.edu/books/little-schemer), by Daniel P. Friedman and Matthias Felleisen
+* [The Little Schemer](http://mitpress.mit.edu/books/little-schemer-fourth-edition), by Daniel P. Friedman and Matthias Felleisen
diff --git a/exercises/difference-of-squares/difference-of-squares-test.rkt b/exercises/difference-of-squares/difference-of-squares-test.rkt
index 31209be0..fb3fd1b2 100644
--- a/exercises/difference-of-squares/difference-of-squares-test.rkt
+++ b/exercises/difference-of-squares/difference-of-squares-test.rkt
@@ -9,14 +9,14 @@
     (test-suite
      "difference of squares"
 
-     (test-eqv? "square-of-sums-to-5" (square-of-sums 5) 225)
+     (test-eqv? "square-of-sum-to-5" (square-of-sum 5) 225)
      (test-eqv? "sum-of-squares-to-5" (sum-of-squares 5) 55)
-     (test-eqv? "difference of-sums-to-5" (difference 5) 170)
-     (test-eqv? "square-of-sums-to-10" (square-of-sums 10) 3025)
+     (test-eqv? "difference-of-squares-to-5" (difference 5) 170)
+     (test-eqv? "square-of-sum-to-10" (square-of-sum 10) 3025)
      (test-eqv? "sum-of-squares-to-10"  (sum-of-squares 10) 385)
-     (test-eqv? "difference of-sums-to-10" (difference 10) 2640)
-     (test-eqv? "square-of-sums-to-100" (square-of-sums 100) 25502500)
+     (test-eqv? "difference-of-squares-to-10" (difference 10) 2640)
+     (test-eqv? "square-of-sum-to-100" (square-of-sum 100) 25502500)
      (test-eqv? "sum-of-squares-to-100" (sum-of-squares 100) 338350)
-     (test-eqv? "difference of-sums-to-100" (difference 100) 25164150)))
+     (test-eqv? "difference-of-squares-to-100" (difference 100) 25164150)))
 
   (run-tests suite))
diff --git a/exercises/difference-of-squares/difference-of-squares.rkt b/exercises/difference-of-squares/difference-of-squares.rkt
index 443493ab..ceb457e0 100644
--- a/exercises/difference-of-squares/difference-of-squares.rkt
+++ b/exercises/difference-of-squares/difference-of-squares.rkt
@@ -1,3 +1,3 @@
 #lang racket
 
-(provide sum-of-squares square-of-sums difference)
+(provide sum-of-squares square-of-sum difference)
diff --git a/exercises/difference-of-squares/example.rkt b/exercises/difference-of-squares/example.rkt
index 6307a5f8..5852b36e 100644
--- a/exercises/difference-of-squares/example.rkt
+++ b/exercises/difference-of-squares/example.rkt
@@ -1,16 +1,16 @@
 #lang racket
 
-(provide sum-of-squares square-of-sums difference)
+(provide sum-of-squares square-of-sum difference)
 
 (define (sum-of-squares n)
   (for/sum
       ([i (in-range (add1 n))])
     (* i i)))
 
-(define (square-of-sums n)
+(define (square-of-sum n)
   (let ([sum (for/sum
                ([i (in-range (add1 n))]) i)])
     (* sum sum)))
 
 (define (difference n)
-  (- (square-of-sums n) (sum-of-squares n)))
+  (- (square-of-sum n) (sum-of-squares n)))