My Schools additional tasks

//Students class average <70%:
//Dear Alena Holligan,
//We look forward to seeing you at summer school, beginning July 1st!

//Student class average >=70% and current grade 9
//Dear Alena Holligan,
//Congratulations on completing your freshman year in High School! We’ll see you on 
September 1st for the start of your sophomore year!

//Student class average >=70% and current grade 10
//Dear Alena Holligan,
//Congratulations on completing your sophomore year in High School! We’ll see you on 
September 1st for the start of your junior year!

//Student class average >=70% and current grade 11
//Dear Alena Holligan,
//Congratulations on completing your junior year in High School! We’ll see you on 
September 1st for the start of your senior year!

//Student class average >= 70% and current grade 12
//Dear Alena Holligan,
//Congratulations! You’ve graduated High School! Don’t forget to come back and visit.

$currentGrade = 16;
$finalAverage = .78;
$messageBody = '';

$message = [
   9  => 'Third form',
  10 => 'Fourth form',
  11 => 'Fifth form',
  12 => 'Lower Sixth form',
  13 => 'Upper Sixth form',
  14 => 'University year 1',
  15 => 'University year 2',
  16 => 'University year 3',
];

$teachers = [
  9  => 'Alan Bennett',
  10 => 'Belinda Carrick',
  11 => 'Carol Dear',
  12 => 'Daryl Walker',
  13 => 'Karl Shoot',
  14 => 'Maggie Rowe',
  15 => 'Gale,Fring',
  16 => 'Walter White',
];

$students = [
  'Paul Adams',
  'Charlotte Rixon',
  'Roman Cage',
  'Kevin Emsden',
  'Ruby White',
  'Claire Dyer',
  'Sean Daily',
  'Sean Warne',
];

$student = $students[rand(0,count($students)-1)];

echo "<h1>";
foreach($students as $student){
    echo "Welcome $student<br/>\n";
}
echo "</h1>";

if (!$student) {
   echo 'Please enter a student name';
} elseif ($currentGrade < 9 || $currentGrade > 16){
      echo 'This is only for high school students. Please enter a grade between 9 & 12';
} else {
    if ($finalAverage < .70) {
        $messageBody = 'We look forward to seeing you at summer school, beginning July 1st!';
    } else {

        switch ($currentGrade) {
        case 9 :
          $messageBody = "Congratulations on completing your $message[9] in High School! We’ll see you on September 1st for the start of your $message[10]!  - $teachers[9]";
      break;

    case 10 :
      $messageBody = "Congratulations on completing your $message[10] in High School! We’ll see you on September 1st for the start of your $message[11]!  - $teachers[10]";
      break;

    case 11 :
      $messageBody = "Congratulations on completing your $message[11] in High School! We’ll see you on September 1st for the start of your $message[12]!  - $teachers[11]";
      break;

    case 12 :
      $messageBody = "Congratulations! You’ve graduated $message[12]! Don’t forget to come back for $message[13].  - $teachers[12]";
      break;

    case 13 :
      $messageBody = "Congratulations! You’ve graduated $message[13]! Best of luck for $message[14].  - $teachers[13]";
      break;

    case 14 :
      $messageBody = "Congratulations! You’ve graduated $message[14]! Best of luck for $message[15].  - $teachers[14]";
      break;

    case 15 :
      $messageBody = "Congratulations! You’ve graduated $message[15]! Best of luck for $message[16].  - $teachers[15]";
      break;

    case 16 :
      $messageBody = "Congratulations! You’ve graduated $message[16]! Best of luck and dont forget to visit!  - $teachers[16]";
      break;

    default :
    $messageBody = 'Error: Grade level not between 9 and 16';
    break;
  }
}
echo "Dear $student\n";
echo $messageBody;
}
?>