Teacher can also view information of the announcement in the list and download the attachment (if any).
He/she can also edit information of the announcement including its message content, attachment, start date, end date,
and also the selected class. Once any update has been made, the system will automatically send Facebook and Twitter
notification to the social network page(s) of each student in the class to inform about the change. However, teacher can
select or deselect the type of notification (i.e. if teacher deselects Twitter, the system will send only Facebook
notification). Moreover, teacher can also delete the existing announcement from the system.