students.php

<!doctype html>
<html>
  <head><meta charset="utf-8"></head>
  <body>
    <h1>Здравствуйте</h1>
    <p>Ваш IP-адрес
      <?php
      echo $_SERVER{'REMOTE_ADDR'};
      ?>
    </p>
    
    <?php
    $group = $_GET['group'];
    ?>
    
    <h2>Группа <?= $group?></h2>
    
    <ol>

      <?php
      $group_list = array();
      $group_list[] = "Иванов";
      $group_list[] = "Петров";
      $group_list[] = "Сидоров";

      foreach ($group_list as $name) {
        echo "<li>$name</li>";
      }

      ?>

    </ol>
  </body>
</html>