Inexpensive wireless driveway alerts or door bells are great at alerting you while you are in ear shot but do not let you know what happened when you are away.
Using a smaller motor as an actuator, wired to the speaker, a moved flag indicates an alert has been triggered.
A plastic cap adds a finishing touch.
Teachers! Did you use this instructable in your classroom?
Add a Teacher Note to share how you incorporated it into your lesson.