tighten/onramp

use App\Completable;
use Illuminate\Database\Eloquent\Model;

class Module extends Model implements Completable
{
    //
    public function completions()
    {
        return $this->morphMany(Completion::class, 'completable');
    }
    //
}

use Illuminate\Foundation\Auth\User as Authenticatable;

class User extends Authenticatable
{
    //
    public function complete(Completable $completable)
    {
        return $this->completions()->create([
            'completable_id' => $completable->getKey(),
            'completable_type' => $completable->getMorphClass(),
        ]);
    }
    //
}

use Illuminate\Database\Eloquent\Model;

class Completion extends Model
{
    //
    public function completable()
    {
        return $this->morphTo();
    }

    public function scopeModules($query)
    {
        return $query->where('completable_type', (new Module)->getMorphClass());
    }

    public function scopeResources($query)
    {
        return $query->where('completable_type', (new Resource)->getMorphClass());
    }

    public function scopeSkills($query)
    {
        return $query->where('completable_type', (new Skill)->getMorphClass());
    }
}