Noodle/htdocs/teacher/header.php

<header>
  <div class="container">
    <img src="../img/logo.png" alt="Noodle logo" class="logo">
    <nav>
      <ul>
        <li><a href="teacher.php">Create questions</a></li>
        <li><a href="teacher.php">Check results</a></li>
        <li><a href="teacher.php">Logout</a></li>
      </ul>
    </nav>
  </div>
</header>