Tightly coupled class example

school.php

class Student {
  private $studentName;
  public __construct($studentName){
    $this->studentName = $studentName;
  }
}

class School {
  private $student;
  private $schoolName;
  public __construct($schoolName, $studentName){    // Here using $studentName in School scope makes School class tightly coupled.
    $this->schoolName = $schoolName;
    $this->student =  new Student($studentName)     
  }
}