laravel Seeder && Factory

I'm trying to seed fake data to tables with faker but here is the error that I get:

Seeder :

<?php

use App\Models\Student;
use Illuminate\Database\Seeder;

class StudentsSeeder extends Seeder
{
    /**
     * Run the database seeds.
     *
     * @return void
     */
    public function run()
    {
        //
        factory(App\Student::class)->create();
    }
}

Factory :

<?php
use Illuminate\Database\Eloquent\Factories\Factory;
use Illuminate\Support\Str;
use Faker\Generator as Faker;

$factory->define(App\Student::class, function (Faker $faker) {
    return [
        //
        'firstName' => $faker->name,
        'fatherName' => $faker->name,
        'gender' => $faker->word,
        'dob' => $faker->date,
        'address' => $faker->sentence(20),
        'email' => $faker->safeEmail,
        'phone' => $faker->str_random(10),
        'created_at' => $faker->timestamp,
        'study_year' => $faker->randomDigit,
    ];

});

• php version -> "^7.1.3",
• "laravel/framework": "5.6.*",