PHP PDO Insertar usando bucle

No necesita vincular sus variables. He hecho esto antes con un código similar. Sin embargo, es difícil decir qué va mal. ¿Obtiene una excepción? Si es así, ¿cuál es?

Lo único que veo mal es que tienes tu preparación dentro del circuito... debería ser más como:

try {
         $conn = new PDO("mysql:host=$host;dbname=$dbName", $un, $pw);
         echo 'Connected to database<br>';

        $sql = "INSERT INTO studentData (originallyAddedOn, inputMethod, studentFirst, studentLast, studentStreet, studentCity, studentState, studentZip, studentDOB, studentGender, studentGrade, schoolName, schoolStreet, schoolCity, schoolState, schoolZip, schoolContactName, schoolContactTitle, schoolContactEmail, schoolContactPhone) VALUES (:originallyAddedOn, :inputMethod, :studentFirst, :studentLast, :studentStreet, :studentCity, :studentState, :studentZip, :studentDOB, :studentGender, :studentGrade, :schoolName, :schoolStreet, :schoolCity, :schoolState, :schoolZip, :schoolContactName, :schoolContactTitle, :schoolContactEmail, :schoolContactPhone)";

        // prepare once... exceute many :-)
        $q = $conn->prepare($sql); 

        foreach($studentDataArray as $student) {
            $q->execute($yourDataArray);
            // do other stuff if needed

        }

} catch(PDOException $e) {
  echo $e->getMessage();
}