class Animal
{
  public static function model(){
    self::getModel();
  }

  protected static function getModel(){
    echo "This is a animal model";
  }
}

Animal::model();

Class Dog extends Animal
{
  protected static function getModel(){
    echo "This is a Dog model";
  }
}

Dog::model();

class Animal
{
  public static function model(){
    static::getModel();
  }

  protected static function getModel(){
    echo "This is a animal model";
  }
}

Animal::model();

Class Dog extends Animal
{
  protected static function getModel(){
    echo "This is a Dog model";
  }
}

Dog::model();