My code looks like it is right and all my dependencies are installed, but why am I getting this error?

Rusie@DESKTOP-05UMA67 MINGW64 ~/Documents/susan_treehouse/Building_a_Rest_API/Test_Routes_With_Postman (master)
$ node app.js
module.js:471
    throw err;
    ^

Error: Cannot find module 'mongooose'
    at Function.Module._resolveFilename (module.js:469:15)
    at Function.Module._load (module.js:417:25)
    at Module.require (module.js:497:17)
    at require (internal/module.js:20:19)
    at Object.<anonymous> (C:\Users\Rusie\Documents\susan_treehouse\Building_a_R
est_API\Test_Routes_With_Postman\app.js:13:16)
    at Module._compile (module.js:570:32)
    at Object.Module._extensions..js (module.js:579:10)
    at Module.load (module.js:487:32)
    at tryModuleLoad (module.js:446:12)
    at Function.Module._load (module.js:438:3)
    at Module.runMain (module.js:604:10)
    at run (bootstrap_node.js:394:7)
    at startup (bootstrap_node.js:149:9)
    at bootstrap_node.js:509:3

'use strict';

var express = require("express");
var app = express();
var routes = require("./routes");

var jsonParser = require("body-parser").json;
var logger = require("morgan");

app.use(logger("dev"));
app.use(jsonParser());

var mongoose = require("mongooose");

mongoose.connect("mongodb://localhost:27017/qa");

var db = mongoose.connection;

db.on("error", function(err){
    console.error("connection error:", err);
});

db.once("open", function(){
    console.log("db connection successful");
});

app.use("/questions", routes);

// catch 404 and forward to error handleer
app.use(function(req, res, next){
    var err = new Error("Not Found");
    err.status = 404;
    next(err);
});

// Error Handler

app.use(function(err, req, res, next){
    res.status(err.status || 500);
    res.json({
        error: {
            message: err.message
        }
    });
});

var port = process.env.PORT || 3000;

app.listen(port, function(){
    console.log("Express server is listening on port", port);
});

'use strict';

var mongoose = require("mongoose");

var Schema = mongoose.Schema;

var sortAnswers = function(a, b) {
    //- negative a before b
    //0 no change
    //+ positive a after back
    if(a.votes === b.votes){
        return b.updatedAt - a.updatedAt;
    }
    return b.votes - a.votes;
}

var AnswerSchema = new Schema({
    text: String,
    createdAt: {type: Date, default: Date.now},
    updatedAt: {type: Date, default: Date.now},
    votes: {type: Number, default:0}
});

AnswerSchema.method("update", function(updates, callback) {
    Object.assign(this, updates, {updatedAt: new Date()});
    this.parent().save(callback);
});

AnswerSchema.method("vote", function(vote, callback) {
    if(vote === "up") {
        this.votes += 1;
    } else {
        this.votes -= 1;
    }
    this.parent().save(callback);
});

var QuestionSchema = new Schema({
    text: String,
    createdAt: {type: Date, default: Date.now},
    answers: [AnswerSchema]
});

QuestionSchema.pre("save", function(next){
    this.answers.sort(sortAnswers);
    next();
});

var Question = mongoose.model("Question", QuestionSchema);

module.exports.Question = Question;

'use strict';

var mongoose = require("mongoose");

mongoose.connect("mongodb://localhost:27017/sandbox");

var db = mongoose.connection;

db.on("error", function(err){
    console.log("connection error:", err);
});

db.once("open", function(){
    console.log("db connection successful");
    // All database communication goes here

    var Schema = mongoose.Schema;
    var AnimalSchema = new Schema({
        type:  {type: String, default: "goldfish"},
        size:  String,
        color: {type: String, default: "golden"},
        mass:  {type: Number, default: 0.007},
        name:  {type: String, default: "Angela"}
});

    AnimalSchema.pre("save", function(next){
        if(this.mass >= 100) {
            this.size = "big";
        } else if (this.mass >= 5 && this.mass < 100) {
            this.size = "medium";
        } else {
            this.size = "small";
        }
        next();
    });

    AnimalSchema.statics.findSize = function(size, callback){
        //this == Animal
        return this.find({size: size}, callback);
    }
    AnimalSchema.methods.findSameColor = function(callback) {
        //this == document
        return this.model("Animal").find({color: this.color}, callback);
    }

    var Animal = mongoose.model("Animal", AnimalSchema);

    var elephant = new Animal({
        type: "elephant",
        color: "gray",
        mass: 6000,
        name: "Lawrence"
    });

    var animal = new Animal({}); //Goldfish

    var whale = new Animal({
        type: "whale",
        mass: 190500,
        name: "Fig"
    });

    var animalData = [
        {
            type: "mouse",
            color: "gray",
            mass: 0.035,
            name: "Marvin"
        },
        {
            type: "nutria",
            color: "brown",
            mass: 6.35,
            name: "Gretchen"
        },
        {
            type: "wolf",
            color: "gray",
            mass: 45,
            name: "Iris"
        },
        elephant,
        animal,
        whale
    ];      

        Animal.remove({}, function(err) {
            if (err) console.error(err);
            Animal.create(animalData, function(err, animals){
                if (err) console.error(err);
                Animal.findOne({type:"elephant"}, function(err, elephant) {
                    elephant.findSameColor(function(err, animals){
                        if (err) console.error(err);
                        animals.forEach(function(animal){
                            console.log(animal.name + " the " + animal.color + " " + animal.type + " is a " + animal.size + "-sized animal.");
                        });
                        db.close(function(){
                            console.log("db connection closed");
                        });
                    });
                });
            });
        });
    }); 

'use strict';

var express = require("express");
var router = express.Router();
var Question = require("./models").Question;

router.param("qID", function(req,res,next,id){
    Question.findById(id, function(err, doc){
        if(err) return next(err);
        if(!doc) {
            err = new Error("Not Found");
            err.status = 404;
            return next(err);
        }
        req.question = doc;
        return next();
    });
});

router.param("aID", function(req,res,next,id){
    req.answer = req.question.answers.id(id);
    if(!req.answer) {
        err = new Error("Not Found");
        err.status = 404;
        return next(err);
    }
    next();
});

// GET /questions
// Route for questions collection
router.get("/", function(req, res, next){
    Question.find({})
                .sort({createdAt: -1})
                .exec(function(err, questions){
                    if(err) return next(err);
                    res.json(questions);
                });
});

// POST /questions
// Route for creating questions
router.post("/", function(req, res, next){
    var question = new Question(req.body);
    question.save(function(err, question){
        if(err) return next(err);
        res.status(201);
        res.json(questions);
    }); 
});

// GET /questions/:id
// Route for specific questions
router.get("/:qID", function(req, res, next){
    res.json(req.question);
});

// POST /questions
// Route for creating an answer
router.post("/:qID/answers", function(req, res, next){
    req.question.answers.push(req.body);
    req.question.save(function(err, question){
        if(err) return next(err);
        res.status(201);
        res.json(question);
    });
});

// PUT /questions/:qID/answers/:aID
// Edit a specific answer
router.put("/:qID/answers/:aID", function(req, res){
    req.answer.update(req.body, function(err, result){
        if(err) return next(err);
        res.json(result);
    });
});

// DELETE ?questions/:qID/answers/:aID
// Delete a specific answer
router.delete("/:qID/answers/:aID", function(req, res){
    req.answer.remove(function(err, question){
        req.question.save(function(err, question){
            if(err) return next(err);
            res.json(question);
        });
    });
});

// POST/questions/:qID/answers/:aID/vote-up
// POST/questions/:qID/answers/:aID/vodte-down
// Vote on a specific answer
router.post("/:qID/answers/:aID/vote-:dir",
    function(req, res, next){
        if(req.params.dir.search(/^(up|down)$/) === -1) {
            var err = new Error("Not Found");
            err.status = 404;
            next(err);
        } else {
            req.vote = req.params.dir;
            next();
        }
    }, 
    function(req, res, next){
        req.answer.vote(req.vote, function(err, question){
            if(err) return next(err);
            res.json(question);
        });
});

module.exports = router;

{
  "name": "Create_An_Express_App",
  "version": "1.0.0",
  "main": "app.js",
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1"
  },
  "keywords": [],
  "author": "",
  "license": "ISC",
  "dependencies": {
    "body-parser": "^1.15.2",
    "express": "^4.13.4",
    "mongoose": "^4.4.20",
    "morgan": "^1.7.0"
  },
  "description": ""
}