A 19th century teachers clicket or clicker used to gain the attention of inattentive pupils. 
 
This one is made from beech wood and is an early example having a trigger held to the head end by a gut loop. Pressure and quick release of the trigger produces a sharp click.
 
Later examples have pivotted spring loaded triggers which were patented.
 
This antique treen teachers clicker measures 30cm l x 5cm at the widest point of the head, not including the trigger.