Sometimes a student may wish to add further work to an assignment or may have submitted the assignment too soon by mistake.

It is not possible for a student to resubmit a piece of work by themselves. As a teacher, you will need to reassign the activity individually to the student. 

However, resubmitting the original assignment will create a duplicate version of the same assignment.  
To ensure that this is just sent to the individual student and not resent to the whole class or group, you will need to select just that student.

At the point of assigning, click Select Pupils and then select the student who needs the assignment resubmitting.