Código PHP:
<?php
session_start();
?>
<!DOCTYPE html PUBLIC "-//WAPFORUM//DTD XHTML Mobile 1.0//EN" "http://www.wapforum.org/DTD/xhtml-mobile10.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>Materias Estudiante</title>
</head>
<body>
Estudainte <?php print $_SESSION['nombre']. "<br>"; ?>
<?php
include('cxn.php');
$sql= mysql_query("SELECT m.nombre_materia, r.Nota FROM tbl_materias AS m, tbl_usuarios AS u, tbl_relacion AS r WHERE m.id_materia=r.id_materia AND u.id_usuario = r.id_usuario AND u.id_usuario ='".$_SESSION['id_usuario']."'") or die (mysql_error());
while ($row = mysql_fetch_array($sql))
{
?>
<table border="1">
<tr align="center" bgcolor="#CC00CC" bordercolor="#000000">
<td>Materia</td>
<td>Definitiva</td>
<tr>
<td><?php print $row['nombre_materia']; ?> </td>
<td><?php print $row['Nota']; ?> </td>
</tr>
<?php } ?>
</tr>
</table>
</body>
</html>