diff --git a/src/index.js b/src/index.js
index 5237ff4..97e29e9 100644
--- a/src/index.js
+++ b/src/index.js
@@ -1,26 +1,76 @@
-export function double ( x ) {
-  return x * 2;
+// export function Animal () {
+//
+// }
+//
+// Animal.prototype.speak = function() {
+//     return 'generic sound';
+// }
+//
+//
+// export function Reptile() {
+//     this.SOUND = 'reptile sound';
+// }
+//
+// export function Primate() {
+//     this.SOUND = 'primate sound';
+// }
+//
+// Reptile.prototype = Object.create(Animal.prototype)
+//
+// Reptile.prototype.speak = function () {
+//     return this.SOUND;
+// };
+//
+//
+// Primate.prototype = Object.create(Animal.prototype)
+//
+// Primate.prototype.speak = function () {
+//     return this.SOUND;
+// }
+//
+// export function Human() {}
+//
+// Human.prototype = Object.create(Primate.prototype)
+//
+// Human.prototype.speak = function (word) {
+//     return word
+// }
+
+// IN ES6
+export class Animal {
+    constructor() {};
+
+    speak() {
+        return 'generic sound';
+    }
 }
 
-export function doubleXTimes ( x, num ) {
-  let result = x;
+export class Reptile extends Animal {
 
-  for ( let i = 1; i <= num; i++ ) {
-    // result = result * 2;
-    result = double( result );
-  }
+    constructor() {
+        super();
+        this.SOUND = 'reptile sound'
+    };
 
-  return result;
-}
 
-export function doubleEach ( arr ) {
-  let result = arr.map( double );
+    speak() {
+        return this.SOUND;
+    }
+}
 
-  // const result = arr.map( x => double( x ) );
-  // const result = arr.map( function ( x ) {
-  //   return double( x );
-  // });
+export class Primate extends Animal {
+    constructor() {
+        super();
+        this.SOUND = 'primate sound'
+    };
 
-  return result;
+    speak() {
+        return this.SOUND;
+    }
 }
 
+export class Human extends Primate {
+    speak(words) {
+        return words;
+    }
+}
diff --git a/src/spec.js b/src/spec.js
index 3e22930..960ba82 100644
--- a/src/spec.js
+++ b/src/spec.js
@@ -1,30 +1,68 @@
 import test from 'tape';
-import { double, doubleXTimes, doubleEach } from './index';
+import {Animal, Reptile, Primate, Human} from './index';
 
-test( 'double fn', function ( test ) {
-  const actual = double( 5 );
-  const expected = 10;
+test('instance', function (test) {
+    const animal = new Animal();
+    test.ok( animal instanceof Animal, 'should create an instance of Animal' );
 
-  test.equal( actual, expected, 'should double the value' );
-
-  test.end();
+    test.end();
 });
 
-test( 'doubleXTimes', function ( test ) {
-  const actual = doubleXTimes( 5, 3 );
-  const expected = 40;
+test('sound', function (test) {
 
-  test.equal( actual, expected, 'should double 5 three times' );
+    const animal = new Animal();
+    const expected = 'generic sound';
+    const actual = animal.speak('generic sound');
 
-  test.end();
+    test.equal( actual, expected, 'should make a generic sound when it speaks' );
+    test.end();
 });
 
-test( 'doubleEach', function ( test ) {
-  const actual = doubleEach([ 0, 1, 2 ]);
-  const expected = [ 0, 2, 4 ];
+test('reptile', function (test) {
+
+    let actual, expected;
+
+    const reptile = new Reptile();
+
+    test.ok( reptile instanceof Reptile, 'should be an instance of Reptile' );
+    test.ok( reptile instanceof Animal, 'should be an instance of Animal' );
+
+    expected = reptile.SOUND;
+    actual = reptile.speak();
+    test.equal( actual, expected, 'should make a reptile sound when it speaks' );
+    test.end();
+})
+
+test('primate', function (test) {
+
+    let actual, expected;
+
+    const primate = new Primate();
 
-  test.deepEqual( actual, expected, 'should double each in the array' );
+    test.ok( primate instanceof Primate, 'should be an instance of Primate' );
+    test.ok( primate instanceof Animal, 'should be an instance of Animal' );
 
-  test.end();
+    expected = primate.SOUND;
+    actual = primate.speak();
+    test.equal( actual, expected, 'should make a primate sound when it speaks' );
+
+    test.end();
 });
 
+test('human', function (test) {
+
+    let actual, expected;
+
+    const human = new Human();
+
+    test.ok( human instanceof Human, 'should be an instance of Human' );
+    test.ok( human instanceof Primate, 'should be an instance of Primate' );
+    test.ok( human instanceof Animal, 'should be an instance of Animal' );
+
+    const message = 'hello';
+    expected = message;
+    actual = human.speak(message);
+    test.equal( actual, expected, 'should speak what it is asked to speak' );
+
+    test.end();
+});