diff --git a/index.js b/index.js
index 00027a1c8..c72d438fb 100644
--- a/index.js
+++ b/index.js
@@ -16,7 +16,8 @@ function myFunction() {
 //myFunction();
 
 //🚀🚀🚀 ⬇️ 📝 Explanation ⬇️ 📝 🚀🚀🚀: 
-
+// "internal" is a variable declared inside the function "myFunction()" making the variable a function scope. The variable "internal" can be access by any method as long as it 
+// is within the "myFunction()" function.
 
 
 
@@ -30,9 +31,12 @@ function myFunction() {
 💡 NOTE: you may use a for loop for this function if you wish 
 */
 
-function summation(/*Your Code Here*/) {
-  /*Your Code Here*/
-
+function summation(arg) {
+  let total = 0;
+  for(let i = 1; i <= arg; i++){
+    total += i;
+  }
+  return total;
   }
  
 
@@ -60,8 +64,12 @@ const zooAnimals = [
   💡 NOTE: the array returned should be an array of strings, and each string should follow this pattern: "name: {name}, scientific: {scientific name}"
   */
 
-  function animalNames(/*Your Code Here*/){
-    /*Your Code Here*/
+  function animalNames(arg){
+    let displayNames = [];
+    arg.forEach(element => {
+      displayNames.push(`name: ${element.animal_name}, scientific: ${element.scientific_name}`)
+    });
+    return displayNames;
   }
   
 
@@ -75,8 +83,10 @@ const zooAnimals = [
   💡 NOTE: Do some research for other methods that can help help you
   */
 
-  function lowerCaseNames(/*Your Code Here*/){
-    /*Your Code Here*/
+  function lowerCaseNames(arg){
+    return arg.map((element) => {
+      return element.animal_name.toLowerCase();
+    })
   }
   
   
@@ -88,8 +98,10 @@ const zooAnimals = [
   3. Return this new array
   */
 
-  function lowPopulationAnimals(/*Your Code Here*/){
-    /*Your Code Here*/
+  function lowPopulationAnimals(arg){
+    return arg.filter((element) => {
+      return element.population < 5;
+    })
   }
   
 
@@ -102,8 +114,10 @@ const zooAnimals = [
   💡 NOTE: Remember the reduce method takes two arguments: a callback (which itself takes two args - the accumulator and the item), and an initial value for the count. Check MDN/W3Schools for syntax!
   */
 
-  function USApop(/*Your Code Here*/){
-    /*Your Code Here*/
+  function USApop(arg){
+    return arg.reduce((accumulator, currentValue) => {
+      return accumulator + currentValue.population;
+    }, 0)
   }
   
   
@@ -116,8 +130,8 @@ const zooAnimals = [
     💡 NOTE: The tests for 'consume' will pass if it is created correctly and also after you correctly complete the functions 'add' and 'greeting' below in Step 2.
   */
 
-  function consume(/*Your Code Here */){
-    /*Your Code Here */
+  function consume(a, b, cb){
+    return cb(a, b);
   }
  
   
@@ -128,8 +142,8 @@ const zooAnimals = [
  2. Return the sum of those numbers
  */
 
-function add(/*Your Code Here */){
-    /*Your Code Here*/
+function add(a, b){
+    return a + b;
   }
 
 
@@ -138,8 +152,8 @@ function add(/*Your Code Here */){
 2. Return the product of those numbers
 */
 
-function multiply(/*Your Code Here */){
-   /*Your Code Here */
+function multiply(a, b){
+   return a * b;
   }
 
 
@@ -149,16 +163,16 @@ function multiply(/*Your Code Here */){
 💡 NOTE: The string returned must match the format above or the test will not pass!
 */
 
-function greeting(/*Your Code Here */){
-   return /*Your Code Here */
+function greeting(firstName, lastName){
+   return `Hello ${firstName} ${lastName}, nice to meet you!`;
   }
   
   
 // 🦁🦁🦁 Step 3: Check your work by un-commenting the following calls to consume(): 🦁🦁🦁 
 // ⬇️ ⬇️ ⬇️ ⬇️ ⬇️ ⬇️ ⬇️ ⬇️ ⬇️ ⬇️ ⬇️
-// console.log(consume(2, 2, add)); // 4
-// console.log(consume(10, 16, multiply)); // 160
-// console.log(consume("Mary", "Poppins", greeting)); // Hello Mary Poppins, nice to meet you!
+console.log(consume(2, 2, add)); // 4
+console.log(consume(10, 16, multiply)); // 160
+console.log(consume("Mary", "Poppins", greeting)); // Hello Mary Poppins, nice to meet you!
 
 
 
@@ -175,24 +189,27 @@ function greeting(/*Your Code Here */){
 - Instances of CuboidMaker should initialize `length`, `width` and `height` properties
 */
 
-function CuboidMaker(/*Your Code Here */){
-  /*Your Code Here */
+function CuboidMaker(arg){
+  this.length = arg.length;
+  this.width = arg.width;
+  this.height = arg.height;
 }
 
-
 /* 🐴🐴🐴 Step 2: Volume Method 🐴🐴🐴
   Create a method called volume using CuboidMaker's prototype that returns the volume of a given cuboid's length, width, and height
   💡 NOTE: Formula for cuboid volume: length * width * height   
 */
-
-
-
+CuboidMaker.prototype.volume = function() {
+  return this.length * this.width * this.height;
+};
 
 /* 🐴🐴🐴 Step 3: Surface Area Method 🐴🐴🐴
   Create another method called surfaceArea using CuboidMaker's prototype that returns the surface area of a given cuboid's length, width, and height. 
   💡 NOTE: Formula for cuboid surface area: 2 * (length * width + length * height + width * height)  
 */
-
+CuboidMaker.prototype.surfaceArea = function() {
+  return 2 * (this.length * this.width + this.length * this.height + this.width * this.height);
+};
 
 
 
@@ -200,29 +217,37 @@ function CuboidMaker(/*Your Code Here */){
   Create an object called cuboid that uses the new keyword to use our CuboidMaker constructor
   Add properties and values of length: 4, width: 5, and height: 5 to cuboid. */
 
-
-
-
+let cuboid = new CuboidMaker({length: 4, width: 5, height: 5});
 
 // 🐴🐴🐴 Test your volume and surfaceArea methods by uncommenting the logs below: 🐴🐴🐴
 // ⬇️ ⬇️ ⬇️ ⬇️ ⬇️ ⬇️ ⬇️ ⬇️
-// console.log(cuboid.volume()); // 100
-// console.log(cuboid.surfaceArea()); // 130
+console.log(cuboid.volume()); // 100
+console.log(cuboid.surfaceArea()); // 130
  
 
 // 🦄🦄🦄 Topic 4: Classes 🦄🦄🦄 //
 //Using CuboidMakerTwo, take your prototypes from above and refactor into class syntax. Then, create an object called cuboidTwo that uses the new keyword to use our CuboidMakerTwo class.
  
 class CuboidMakerTwo{
-
+  constructor(arg) {
+    this.length = arg.length;
+    this.width = arg.width;
+    this.height = arg.height;
+  }
+  volume() {
+    return this.length * this.width * this.height;
+  }
+  surfaceArea() {
+    return 2 * (this.length * this.width + this.length * this.height + this.width * this.height);
+  }
 }
-
+const cuboidTwo = new CuboidMakerTwo({length: 4, width: 5, height: 5});
 
 
 
 //🦄🦄🦄 Test your volume and surfaceArea methods by uncommenting the logs below: 🦄🦄🦄
-// console.log(cuboidTwo.volume()); // 100
-// console.log(cuboidTwo.surfaceArea()); // 130
+console.log(cuboidTwo.volume()); // 100
+console.log(cuboidTwo.surfaceArea()); // 130