public function toForm(){
        $returnValue = null;

        $interaction = $this->getAssociatedInteraction();
        if($interaction instanceof Interaction){
            $responseFormClass = '\\oat\\taoQtiItem\\controller\\QTIform\\response\\'.ucfirst(strtolower($interaction->getType())).'Interaction';
            if(class_exists($responseFormClass)){
                $formContainer = new $responseFormClass($this);
                $myForm = $formContainer->getForm();
                $returnValue = $myForm;
            }
        }else{
            throw new Exception('cannot find the parent interaction of the current response');
        }

        return $returnValue;
    }