diff --git a/paperproblems/array-functions/problem1.txt b/paperproblems/array-functions/problem1.txt
index 8e97911..a79f195 100644
--- a/paperproblems/array-functions/problem1.txt
+++ b/paperproblems/array-functions/problem1.txt
@@ -13,4 +13,6 @@ var dogs = animals.filter(
                 function(animal)
                      {return animal.species === 'dog';});
 
-console.log(dogs.length);
\ No newline at end of file
+console.log(dogs.length);
+
+//2
\ No newline at end of file
diff --git a/paperproblems/array-functions/problem2.txt b/paperproblems/array-functions/problem2.txt
index e9050e5..2378ffc 100644
--- a/paperproblems/array-functions/problem2.txt
+++ b/paperproblems/array-functions/problem2.txt
@@ -13,4 +13,6 @@ var letterN = animals.filter(function(animal) {
     return animal.name !== undefined && animal.name[0] === 'N'
 });
 
-console.log(letterN[0].name);
\ No newline at end of file
+console.log(letterN[0].name);
+
+//Nacho
\ No newline at end of file
diff --git a/paperproblems/array-functions/problem3.txt b/paperproblems/array-functions/problem3.txt
index e1182ab..430f697 100644
--- a/paperproblems/array-functions/problem3.txt
+++ b/paperproblems/array-functions/problem3.txt
@@ -10,4 +10,6 @@ var animals = [
 var animalNames = animals.map(
                     function(animal) {return animal.name});
 
-console.log(animalNames.join());
\ No newline at end of file
+console.log(animalNames.join());
+
+//Nacho,Ramses,Flufftail,Popcorn,Neckbeard,
\ No newline at end of file
diff --git a/paperproblems/array-functions/problem4.txt b/paperproblems/array-functions/problem4.txt
index 8b933aa..ae47d6a 100644
--- a/paperproblems/array-functions/problem4.txt
+++ b/paperproblems/array-functions/problem4.txt
@@ -11,8 +11,8 @@ function isDog(animal) {
     return animal.species === 'dog';
 }
 
-animals.some(isDog)
-animals.every(isDog)
+animals.some(isDog) //true
+animals.every(isDog) //false
 
 
 
diff --git a/paperproblems/arrow-functions/problem1.txt b/paperproblems/arrow-functions/problem1.txt
index 7338e61..1604e4f 100644
--- a/paperproblems/arrow-functions/problem1.txt
+++ b/paperproblems/arrow-functions/problem1.txt
@@ -2,18 +2,18 @@ For each of the following expressions:
  - Does it have a syntax error?
  - If it doesn't have a syntax error, what are the probable input and output types of the function?
 
-a) x => x + 1
+a) x => x + 1  //no syntax error, input type: number, output type: number
 
-b) x, y => x * y
+b) x, y => x * y //need () for the arguments, input type: number, output type: number
 
-c) x => { x * 2 }
+c) x => { x * 2 } //need no {} OR a return before x*2, input type: number, output type: number
 
-d) (x, z) => {console.log(z); return x * z}
+d) (x, z) => {console.log(z); return x * z} //no syntax error, input type: number, output type: number
 
-e) x => console.log(z); return x * z
+e) x => console.log(z); return x * z //need {} andz must be defined, input type: number, output type: number
 
-f) (x) => x * 2
+f) (x) => x * 2 //ok but you remove () for the parameter, input type: number, output type: number
 
-e) () => console.log("hello")
+e) () => console.log("hello") //no syntax error, input type: none, output type: string
 
 When you're done, check all your answers in the developer console.
\ No newline at end of file
diff --git a/paperproblems/callbacks/problem1.txt b/paperproblems/callbacks/problem1.txt
index 63df256..07631a5 100644
--- a/paperproblems/callbacks/problem1.txt
+++ b/paperproblems/callbacks/problem1.txt
@@ -12,4 +12,6 @@ function h() {
     setTimeout(f, 1000);
 }
 
-setTimeout(h, 200);
\ No newline at end of file
+setTimeout(h, 200);
+
+//This programme log "Hello!" after 1700 ms
\ No newline at end of file
diff --git a/paperproblems/callbacks/problem2.txt b/paperproblems/callbacks/problem2.txt
index 1ee06dd..8e51fa2 100644
--- a/paperproblems/callbacks/problem2.txt
+++ b/paperproblems/callbacks/problem2.txt
@@ -8,4 +8,9 @@ function h() {
     setInterval(g, 1000);
 }
 
-setInterval(h, 1000);
\ No newline at end of file
+setInterval(h, 1000);
+
+//This program calls h() every second
+//h() calls g() every second
+//g() logs "Hello!"
+//There is an "Hello!" more at each call
\ No newline at end of file
diff --git a/paperproblems/classes/problem1.txt b/paperproblems/classes/problem1.txt
index 9fbc41e..2a0b610 100644
--- a/paperproblems/classes/problem1.txt
+++ b/paperproblems/classes/problem1.txt
@@ -11,4 +11,4 @@ class Dog {
     }
 }
 
-var someDog = new Dog("schnitzel", 2, "male");
+var someDog = new Dog("schnitzel", 2, "male");
\ No newline at end of file
diff --git a/paperproblems/classes/problem2.txt b/paperproblems/classes/problem2.txt
index 60891b1..8a2ca81 100644
--- a/paperproblems/classes/problem2.txt
+++ b/paperproblems/classes/problem2.txt
@@ -12,11 +12,15 @@ class Person {
     }
     toString() {
         return "My name is " + this.name +
-          "and I'm " + this.age + " and I make " + this.salary;
+          " and I'm " + this.age + " and I make " + this.salary;
     }
 }
 
 var bob = new Person(25, "Bob", 40000);
 
 bob.increaseSalary(-500);
-console.log(bob.toString());
\ No newline at end of file
+console.log(bob.toString());
+
+//output: 
+Yay!
+My name is Bob and I'm 25 and I make 39500
\ No newline at end of file
diff --git a/paperproblems/conditional-operator/problem1.txt b/paperproblems/conditional-operator/problem1.txt
index fabd9e8..09083b8 100644
--- a/paperproblems/conditional-operator/problem1.txt
+++ b/paperproblems/conditional-operator/problem1.txt
@@ -4,4 +4,6 @@ function f(x) {
     return x < 5 ? 3 : x > 8 ? 4 : x == 6 ? 12 : 9;
 }
 
-console.log(f(5));
\ No newline at end of file
+console.log(f(5));
+
+//output : 9
\ No newline at end of file
diff --git a/paperproblems/constructor-functions/problem2.txt b/paperproblems/constructor-functions/problem2.txt
index 4cb7dd9..bbe1ef5 100644
--- a/paperproblems/constructor-functions/problem2.txt
+++ b/paperproblems/constructor-functions/problem2.txt
@@ -12,4 +12,6 @@ var bob = new Person("Bob", 30);
 
 Person.prototype.leave = function() {return this.name + " is leaving";}
 
-bob.leave();
\ No newline at end of file
+bob.leave();
+
+//output "Bob is leaving" because the property leave is correctly added to the prototype of the function Person
\ No newline at end of file
diff --git a/paperproblems/constructor-functions/problem3.txt b/paperproblems/constructor-functions/problem3.txt
index 2c875ee..e4127f4 100644
--- a/paperproblems/constructor-functions/problem3.txt
+++ b/paperproblems/constructor-functions/problem3.txt
@@ -16,4 +16,6 @@ Person.prototype.salary = Person.prototype.salary + 300;
 Person.__proto__.salary = Person.__proto__.salary + 400;
 bob.salary = bob.salary + 50;
 
-console.log(bob.salary);
\ No newline at end of file
+console.log(bob.salary);
+
+// output : 40450 because line 16 needs a "prototype" instead of "__proto__" 
\ No newline at end of file
diff --git a/paperproblems/constructor-functions/problem4.txt b/paperproblems/constructor-functions/problem4.txt
index 10d57df..720fc18 100644
--- a/paperproblems/constructor-functions/problem4.txt
+++ b/paperproblems/constructor-functions/problem4.txt
@@ -12,4 +12,6 @@ var bob = Person("Bob", 30);
 
 bob.name = bob.name + " Dole";
 
-bob.greet();
\ No newline at end of file
+bob.greet();
+
+//output: error because the var bob need to use the constructor to define all its properties : var bob = new Person("Bob", 30)
\ No newline at end of file
diff --git a/paperproblems/constructor-functions/problem5.txt b/paperproblems/constructor-functions/problem5.txt
index 70770f4..f4642c0 100644
--- a/paperproblems/constructor-functions/problem5.txt
+++ b/paperproblems/constructor-functions/problem5.txt
@@ -11,4 +11,13 @@ function Person(name, age) {
 }
 
 var bob = new Person("Bob", 30);
+
+
+function person(name, age) {
+    return {fname: name, age: age, greet: function(){console.log("Hello my name is " + name)}}
+}
+
+var bob = person('Bob', 30)
+
 var sue = new Person("Sue", 24);
+
diff --git a/paperproblems/inheritance/problem1.txt b/paperproblems/inheritance/problem1.txt
index 3de989f..1cf3156 100644
--- a/paperproblems/inheritance/problem1.txt
+++ b/paperproblems/inheritance/problem1.txt
@@ -24,4 +24,6 @@ class Square extends Shape {
 }
 
 var s = new Square(5);
-console.log(s.toString());
\ No newline at end of file
+console.log(s.toString());
+
+//output : square with area 25 and perimeter 20
\ No newline at end of file
diff --git a/paperproblems/inheritance/problem2.txt b/paperproblems/inheritance/problem2.txt
index f9d6898..b378c8d 100644
--- a/paperproblems/inheritance/problem2.txt
+++ b/paperproblems/inheritance/problem2.txt
@@ -11,3 +11,20 @@ class Shape {
           this.area() + " and perimeter " + this.perimeter();
     }
 }
+
+class Rectangle extends Shape {
+    constructor(height, width) {
+        super("rectangle");
+        this.height = height;
+        this.width = width;
+    }
+    area() {
+        return this.height * this.width;
+    }
+    perimeter() {
+        return this.height * 2 + this.width * 2;
+    }
+}
+
+var s = new Rectangle(5,3);
+console.log(s.toString());
\ No newline at end of file
diff --git a/paperproblems/variable-scoping/problem1.txt b/paperproblems/variable-scoping/problem1.txt
index 281bdd6..17e7be8 100644
--- a/paperproblems/variable-scoping/problem1.txt
+++ b/paperproblems/variable-scoping/problem1.txt
@@ -9,3 +9,7 @@ function f() {
 
 f();
 f();
+
+//output:
+2
+4
\ No newline at end of file
diff --git a/paperproblems/variable-scoping/problem2.txt b/paperproblems/variable-scoping/problem2.txt
index eb70c9d..94676fc 100644
--- a/paperproblems/variable-scoping/problem2.txt
+++ b/paperproblems/variable-scoping/problem2.txt
@@ -7,4 +7,8 @@ function f() {
 }
 
 f();
-f();
\ No newline at end of file
+f();
+
+output:
+2
+2
\ No newline at end of file
diff --git a/paperproblems/variable-scoping/problem3.txt b/paperproblems/variable-scoping/problem3.txt
index ba8ada5..18da6dc 100644
--- a/paperproblems/variable-scoping/problem3.txt
+++ b/paperproblems/variable-scoping/problem3.txt
@@ -11,4 +11,10 @@ function f() {
 
 f();
 f();
-console.log(y);
\ No newline at end of file
+console.log(y);
+
+//output:
+
+7
+9
+3
\ No newline at end of file
diff --git a/paperproblems/variable-scoping/problem4.txt b/paperproblems/variable-scoping/problem4.txt
index 2294b2e..ff56505 100644
--- a/paperproblems/variable-scoping/problem4.txt
+++ b/paperproblems/variable-scoping/problem4.txt
@@ -14,4 +14,6 @@ function f() {
         }
 
     }
-}
\ No newline at end of file
+}
+
+//variables in scope: f, y, g, z, h and p
\ No newline at end of file
diff --git a/src/HOF/problem1.js b/src/HOF/problem1.js
index 0ed585e..9790105 100644
--- a/src/HOF/problem1.js
+++ b/src/HOF/problem1.js
@@ -1,18 +1,25 @@
-
 function callNoException(f, arg) {
-    // if f(arg) throws an exception, return null
-    // otherwise return what f(arg) returned
-    // Example:
-    //  function throwsZero(x){
-    //     if(x==0) throw new Error("woops");
-    //     return x;
-    //  }
-    //  callNoException(throwsZero, 0) returns null
-    //  callNoException(throwsZero, 12) returns 12
+    try {
+        f(arg);
+        return f(arg);
+    }
+    catch(err) {
+        return null;
+    }
 }
 
-function callNoNull(f, arg) {
-    // if f(arg) returns null, throw an exception
+// if f(arg) throws an exception, return null
+// otherwise return what f(arg) returned
+// Example:
+//  function throwsZero(x){
+//     if(x==0) throw new Error("woops");
+//     return x;
+//  }
+//  callNoException(throwsZero, 0) returns null
+//  callNoException(throwsZero, 12) returns 12
+
+//
+// if f(arg) returns null, throw an exception
     // otherwise return what f(arg) returned  
     // Example: 
     //  function nullZero(x) {
@@ -21,11 +28,66 @@ function callNoNull(f, arg) {
     //  }
     // callNoNull(nullZero, 0) throws an exception
     // callNoNull(nullZero, 12) returns 12
+function callNoNull(f, arg) {
+        var ret = f(arg);
+        if(ret === null) throw new Error("oh no!");
+        return ret
+}
+
+
+
+/* si callNoNull retourne une fonction :
+function callNoNull(f, arg) {
+    function g() {
+        var ret = f(arg);
+        if(ret === null) throw new Error("oh no!");
+        return ret
+    }
+    return g;
+}
+*/
+
+/*
+function callNoNull(f, arg) {
+    if(f(arg) === null) throw "arg is null";
+    return f(arg);
+    }
     
+function nullZero(x) {
+    if(x==0) return null;
+    return x;
+}
     
+try {
+    callNoNull(nullZero, 12)
+    } catch(err) {
+    console.log(err)
 }
+*/
+
+//
+function exceptionalize(f) { 
+    return function(arg) {
+        if (f(arg) == null) {throw 'arg is null';}
+        else return f(arg);
+    }
+}
+
+/*function exceptionalize(f) {
+    return f();
+}
+
+function nullZero(x) {
+    if(x==0) return null;
+    return x;
+}
+
+function g(arg) {
+    if(nullZero(arg) === "null") throw "arg is null";
+    return g(arg)
+}
+*/
 
-function exceptionalize(f) {
     // returns a new function
     // this function takes 1 input, called arg
     // if f(arg) is null, this new function throws an exception
@@ -40,8 +102,8 @@ function exceptionalize(f) {
     // g(0) throws an exception
     // g(12) returns 12
 
-}
 
+//
 function nullify(f) {
     // returns a new function
     // this function takes 1 input, called arg
@@ -55,23 +117,42 @@ function nullify(f) {
     //  nullify(throwsZero) returns a function g such that
     //  g(0) returns null
     //  g(12) throws an exception
-    
+    function g(arg) {
+        try {
+            return f(arg);
+        } catch (err) {
+            return null;
+        }
+    }
+    return g;
 }
 
+
+//
 function map(lst, f) {
-    // lst is an array and f is a function
-    // map returns an array with the same number of elements as lst
-    // if lst = [a1, a2, a3, a4, a5] then map(lst, f) returns [f(a1), f(a2), f(a3), f(a4), f(a5)]
-    // map returns a new array created by applying f
-    //   to the elements of the original array
-    //
-    // Example
-    //
-    // function toUpperCase(str) { return str.toUpperCase(); }
-    // map(["bob", "susie"], toUpperCase) returns ["BOB", "SUSIE"]
+    var ret = [];
+    for (index in lst) {
+      ret.push(f(lst[index]));
+    }
+    return ret;
+  }
+  
+  function toUpperCase(str) { return str.toUpperCase(); }
+  map(["bob", "susie"], toUpperCase)
+
+
+  //
+
+  function filter(lst, f) {
+    var arr = [];
+    for(var i = 0; i < lst.length; i++) {
+      if(f(lst[i]) == true) {
+        arr.push(lst[i]);
+      }
+  }
+  return arr;
 }
 
-function filter(lst, f) {
     // lst is an array and f is a function
     // f takes one argument and returns a boolean (true or false)
     // filter(lst, f) returns a list with all the elements of lst that does not satisfy f removed
@@ -79,11 +160,10 @@ function filter(lst, f) {
     // if lst_ = filter(lst, f) and x is an element of lst_ it means that:
     //     x is an element of lst
     //     f(x) is true  
-    //   
+      
     // Example:
     // function isEven(x) {return x % 2 == 0;}
     // filter([1, 2, 3, 4, 5], isEven) returns [2,4];   
-}
 
 function every(lst, f) {
     // lst is an array and f is a function
@@ -92,7 +172,14 @@ function every(lst, f) {
     
     // Example
     // every([2,4,12], x => x % 2 == 0) returns true
-    // every([2,3,12], x => x % 2 == 0) returns false    
+    // every([2,3,12], x => x % 2 == 0) returns false 
+    for(var i = 0; i < lst.length; i++) {
+        if(f(lst[i]) === false) {
+            return false;
+        }
+        
+    }  
+    return true;  
 }
 
 
@@ -104,4 +191,4 @@ module.exports = {
     map, 
     filter, 
     every
-};
+};
\ No newline at end of file
diff --git a/src/__proto__/problem1.js b/src/__proto__/problem1.js
index 820a78d..540455e 100644
--- a/src/__proto__/problem1.js
+++ b/src/__proto__/problem1.js
@@ -1,6 +1,6 @@
 // Make parent the __proto__ of child
 
 var parent = {x: 5, y: 6, z: 8};
-var child = {x : 10};
+var child = {x : 10, __proto__: parent};
 
 module.exports = {parent, child}
\ No newline at end of file
diff --git a/src/anonymous-functions/problem1.js b/src/anonymous-functions/problem1.js
index c9cdf24..4e06179 100644
--- a/src/anonymous-functions/problem1.js
+++ b/src/anonymous-functions/problem1.js
@@ -6,7 +6,9 @@ function c(g, h) {
 }
 
 function t() {
-    return c(function (x) {return y + 1}, function (y) {return x * 2});
+
+    return c(function g(x) {return x + 1}, function h(y) {return y * 2});
+
 }
 
 module.exports = t;
diff --git a/src/array-functions/problem1.js b/src/array-functions/problem1.js
index 06bc426..103eb67 100644
--- a/src/array-functions/problem1.js
+++ b/src/array-functions/problem1.js
@@ -1,20 +1,38 @@
 function removeEvens(lst) {
+    var arr = [];
+    for (var i = 0; i < lst.length; i++) {
+        if(lst[i] % 2 === 1) arr.push(lst[i])
+    }
+    return arr;
     // lst is an array of numbers
     // Returns a new list with all the even numbers of lst removed
 }
 
 function keepLong(lst) {
+    var arr = [];
+    for (var i = 0; i < lst.length; i++) {
+        if(lst[i].length > 5) arr.push(lst[i]) 
+    }
+    return arr;
     // lst is an array of strings
     // Returns a new list with all the elements of lst that are length greater than 5
 }
 
 function greet(lst) {
+    var x = lst.map(function(i) {return "Hello " + i});
+    return x;
+    }
     // lst is an array of strings
     // Adds "Hello " to every element of greet
     // For example: greet(["bob", "eric"]) returns ["Hello bob", "Hello eric"]
-}
 
 function greetLong(lst) {
+    var arr = [];
+    for (var i = 0; i < lst.length; i++) {
+        if(lst[i].length > 3) arr.push(lst[i]) 
+    }
+    var x = arr.map(function(i) {return "Hello " + i});
+    return x
     // lst is an array of strings
     // Only greet people who's names have length at least 4.
     // Otherwise ignore them completely.
@@ -22,6 +40,9 @@ function greetLong(lst) {
 }
 
 function allLong(lst) {
+    for (i of lst) {
+        return i.length >= 5 ? true : false;
+    }
     // lst is an array of strings
     // Returns true if every element of lst is of length at least 5. Otherwise returns false.
 }
diff --git a/src/arrow-functions/problem1.js b/src/arrow-functions/problem1.js
index 5c0873a..a50775a 100644
--- a/src/arrow-functions/problem1.js
+++ b/src/arrow-functions/problem1.js
@@ -6,7 +6,7 @@ function c(g, h) {
 }
 
 function t() {
-    return c( x => return y + 2, (x,y) => return x + y);
+    return c( x => x + 2, (x,y) => x + y);
 }
 
 module.exports = t
diff --git a/src/arrow-functions/problem2.js b/src/arrow-functions/problem2.js
index 1ae3fdb..91f9741 100644
--- a/src/arrow-functions/problem2.js
+++ b/src/arrow-functions/problem2.js
@@ -1,9 +1,16 @@
 // Convert all the arrow functions to normal anonymous functions
 // There should be no arrows by the end
 
-var x = x => x + 1;
-var y = (x, y) => x + y;
-var z = x => {var y = (x * 7) % 2; return y * 2};
+// var x = x => x + 1;
+// var y = (x, y) => x + y;
+// var z = x => {var y = (x * 7) % 2; return y * 2};
+
+var x = function(x) {return x + 1};
+var y = function(x, y) {return x + y};
+var z = function (x) {
+    var y = (x * 7) % 2;
+    return y * 2;
+}
 
 module.exports = {x, y, z};
 
diff --git a/src/bind/problem1.js b/src/bind/problem1.js
index da0b2d6..91594a8 100644
--- a/src/bind/problem1.js
+++ b/src/bind/problem1.js
@@ -1,7 +1,7 @@
 var bob = {name: "Bob"};
-function greet() {
+var greet = function() {
     return "I'm " + this.name;
 }
 // bind greet to bob
-
+greet = greet.bind(bob);
 module.exports = greet;
\ No newline at end of file
diff --git a/src/bind/problem2.js b/src/bind/problem2.js
index 079a343..15d7f8f 100644
--- a/src/bind/problem2.js
+++ b/src/bind/problem2.js
@@ -1,9 +1,9 @@
 // Fix all the errors in this program
 var dog = {breed: "schnitzel"};
-function greet() {
-    return "I'm a " + this.bred;
+var greet = function() {
+    return "I'm a " + this.breed;
 }
 
-greet.bind(dog);
+greet = greet.bind(dog);
 
 module.exports = greet;
\ No newline at end of file
diff --git a/src/callbacks/problem1.js b/src/callbacks/problem1.js
index 0e8eb76..9f04106 100644
--- a/src/callbacks/problem1.js
+++ b/src/callbacks/problem1.js
@@ -1,7 +1,7 @@
 // Fix all the errors. It should print hello after 1 second
 
 function shout(x) {
-    console.log(x.toUppercase());
+    console.log(x.toLowerCase());
 }
 
-SetTimeout(shout("hello"), 1);
\ No newline at end of file
+setTimeout(shout, 1000, "hello");
\ No newline at end of file
diff --git a/src/classes/problem1.js b/src/classes/problem1.js
index 8e1bcc9..1924c49 100644
--- a/src/classes/problem1.js
+++ b/src/classes/problem1.js
@@ -1,4 +1,12 @@
 class Dog {
+    constructor(age, name, breed) {
+        this.age = age;
+        this.name = name;
+        this.breed = breed;
+    }
+    bark() {
+        return "woof!"
+    }
     // Dog has a constructor with three arguments (in this order): age, name and breed
     // Dog has three attributes: age, name and breed
     // Dog has a method bark, which returns a string    
diff --git a/src/conditional-operator/problem1.js b/src/conditional-operator/problem1.js
index af6e31d..ed2f727 100644
--- a/src/conditional-operator/problem1.js
+++ b/src/conditional-operator/problem1.js
@@ -1,23 +1,11 @@
-//Remove the if statements from these functions.
-//Replace them with the conditional operator
-
 
 function desirability(x) {
-    if(x == 'Brad Pitt') {
-        return "very desirable";
-    } else {
-        return "not so desirable";
-    }
+   return x == 'Brad Pitt' ? "very desirable" : "not so desirable";
 }
 
+
 function broadenHorizon(x) {
-    if(x == 'Brad Pitt') {
-        return "very desirable";
-    } else if(x == 'Angelina Jolie') {
-        return "also desirable";
-    } else {
-        return "not desirable";
-    }
+    return x == 'Brad Pitt'? "very desirable" : x == 'Angelina Jolie'? "also desirable" : "not desirable";
 }
 
-module.exports = {desirability, broadenHorizon}
\ No newline at end of file
+module.exports = {desirability, broadenHorizon}
diff --git a/src/conditional-operator/problem2.js b/src/conditional-operator/problem2.js
index 2dd85bf..a238e42 100644
--- a/src/conditional-operator/problem2.js
+++ b/src/conditional-operator/problem2.js
@@ -2,11 +2,14 @@
 // Replace them with if statements
 
 function iLike(x) {
-    return x == 'chinese food' ? true : false;
+    if(x == 'chinese food') return true 
+    else return false;
 }
 
 function iLikeLessPicky(x) {
-    return x == 'chinese food' ? true : x == 'french food' ? true : false;
+    if(x == 'chinese food') return true 
+    else if(x == 'french food') return true 
+    else return false;
 }
 
 module.exports = {iLike, iLikeLessPicky};
\ No newline at end of file
diff --git a/src/constructor-functions/problem1.js b/src/constructor-functions/problem1.js
index b39887c..8d74d34 100644
--- a/src/constructor-functions/problem1.js
+++ b/src/constructor-functions/problem1.js
@@ -1,2 +1,8 @@
 // Add a function to all arrays called isNotEmpty
 // isNotEmpty returns true is the array is empty, false otherwise
+
+var x = new Array();
+Array.prototype.isNotEmpty = function() {
+    if (this.length !== 0) return true;
+    else return false;
+}
diff --git a/src/exceptions/problem1.js b/src/exceptions/problem1.js
index f54c8f8..5b631fd 100644
--- a/src/exceptions/problem1.js
+++ b/src/exceptions/problem1.js
@@ -1,22 +1,46 @@
 function first(arr) {
+    if(Array.isArray(arr) === false) {
+        throw new Error("it's not an array")
+        } else if(arr.length === 0) {
+            throw new Error("empty array");
+        } else return arr[0]
+    }
+    try {
+        first([1,2]) 
+    } catch(err) {
+        console.log(err)
+    }
     // Throw an exception if the array has no elements
     // Otherwise return the first element
-}
 
 function detective(i) {
     function suspect(i) {
         if(i * 7 % 3 == 0) throw new Error("Bad i!");
     }
+    if(suspect(i) !== "Bad i!") return "everything is ok"
+ }  
+   
+try {
+    detective();
+    return "everything is ok"
+    } catch(err) {
+        return "something fishy"
+}
     // detective checks to see if the suspect throws an exception on input i.
     // Returns "everything ok" if the suspect doesn't. 
     // Returns "something fishy" if the suspect does.
-}
+
 
 function assignFlight(name) {
     var flightNumber = ((name.length * 7) % 20) + "0";
     var terrorSuspects = ["bob", "eric", "susie"];
+    for (var i = 0; i < terrorSuspects.length; i++) {
+        if(name === terrorSuspects[0] || name === terrorSuspects[1] || name === terrorSuspects[2]) {
+        throw new Error("He is suspect")
+        } else return flightNumber
+    }
     // if the name is a terror suspect, throw an exception
     // Otherwise, return the flight number
 }
 
-module.exports = {first, detective, assignFlight}
\ No newline at end of file
+module.exports = {first, detective, assignFlight}
diff --git a/src/inheritance/problem1.js b/src/inheritance/problem1.js
index 71e66b5..869e0ba 100644
--- a/src/inheritance/problem1.js
+++ b/src/inheritance/problem1.js
@@ -4,8 +4,20 @@ class Shape {
     }
 }
 
-class Rectangle {
-
+class Rectangle extends Shape {
+    constructor(width, heigth) {
+        super();
+        this.width = width;
+        this.heigth = heigth;
+    }
+    area() {
+        if (this.width !== this.height) return this.width * this.heigth
+        else return this.size * this.size;
+    }
+    perimeter() {
+        if (this.width !== this.height) return this.width * 2 + this.heigth * 2 
+        else return this.size * 4;
+    }
     // A rectangle is a shape
     // Every rectangle has a width and a height
     // Implement the constructor
@@ -13,7 +25,12 @@ class Rectangle {
     // The constructor has two arguments: width and height
 }
 
-class Square {
+class Square extends Rectangle{
+    constructor(size) {
+        super();
+        this.size = size;
+    }
+
     // A square is a rectangle
     // Every square has a width and a height
     // The height and width of a square are always the same
@@ -23,4 +40,5 @@ class Square {
 }
 
 
+
 module.exports = {Shape, Rectangle, Square};
\ No newline at end of file
diff --git a/src/inheritance/problem2.js b/src/inheritance/problem2.js
index f74dc6b..3e040c0 100644
--- a/src/inheritance/problem2.js
+++ b/src/inheritance/problem2.js
@@ -2,25 +2,28 @@
 
 class Shape {
     constructor(shapeName) {
-        this.shapName = shapeName;
+        this.shapeName = shapeName;
     }
     toString() {
         return this.shapeName + " with area " +
-          this.area() + " and perimeter " + this.permeter();
+          this.area() + " and perimeter " + this.perimeter();
     }
 }
 
-class Square {
+class Square extends Shape {
     constructor(size) {
-        supr("square");
+        super("square");
         this.size = size;
     }
     area() {
-        return this.size * this.siz;
+        return this.size * this.size;
     }
     perimeter() {
        return this.size * 4;
     }
 }
 
+var s = new Square(5)
+console.log(s.toString())
+
 module.exports = {Shape, Square};
\ No newline at end of file
diff --git a/src/return/problem1.js b/src/return/problem1.js
index c8f7b32..084e59f 100644
--- a/src/return/problem1.js
+++ b/src/return/problem1.js
@@ -3,13 +3,7 @@
 // Also, remove these comments
 
 function f(x) {
-    if(x > 10) {
-        return "hello";
-    } else if(x > 5) {
-        return "goodbye";
-    } else {
-        return undefined;
-    }
+    return x > 10 ? "hello" : x > 5 ? "goodbye" : undefined;
 }
 
 module.exports = f; // Don't delete this line but remove this comment.
diff --git a/src/syntax-errors/problem1.js b/src/syntax-errors/problem1.js
index a798e0c..d8c08f9 100644
--- a/src/syntax-errors/problem1.js
+++ b/src/syntax-errors/problem1.js
@@ -1,7 +1,7 @@
 for(var i = 0; i < 10; i++) {
     for(var j = 0; j < 10; j++) {
         for(var k = 0; k < 10; k++) {
-            if(i < k) 
+            if(i < k) {
                 if( k < j) {
                     console.log(i + j + k)
                 }
diff --git a/src/syntax-errors/problem2.js b/src/syntax-errors/problem2.js
index 63643d3..9ae4d99 100644
--- a/src/syntax-errors/problem2.js
+++ b/src/syntax-errors/problem2.js
@@ -14,7 +14,7 @@ var myObj = {
     },
 
     beers: function() {
-        function g(){}}
+        function g(){}
         
         // lots and lots of code
     },
diff --git a/src/this/problem1.js b/src/this/problem1.js
index b7b2740..e852681 100644
--- a/src/this/problem1.js
+++ b/src/this/problem1.js
@@ -1,6 +1,7 @@
 'use strict';
 function whatsMyAgeAgain() {
     // returns this.age unless this is not defined. If this is not defined, return 18
+  if(this === undefined) return 18;
+  else return this.age;
 }
-
 module.exports = whatsMyAgeAgain;
\ No newline at end of file
diff --git a/src/variable-scoping/problem1.js b/src/variable-scoping/problem1.js
index da8f429..a0af8d1 100644
--- a/src/variable-scoping/problem1.js
+++ b/src/variable-scoping/problem1.js
@@ -3,8 +3,9 @@
 // The first time it is called it returns 1
 // Every call thereafter returns a number one greater than the last
 
+var x = 0; 
+
 function f() {
-    var x = 0;  
     x = x + 1;
     return x;
 }