Some Surveys allow you to track who has completed it. It does this by creating slightly different web addresses for each questionnaire (although the questions are the same).

To set this up you will need to create a name in your Survey Software for this unique parameter (Survey Monkey calls this parameter a ‘Custom Variable’).
Then enter the name into this field.
This system will automatically add the Volunteer ID number to the end of your questionnaire Web Address.
Example:
Survey Link: http://mysurvey.com
Volunteer ID Parameter Name: VolID
Once the volunteer has logged their hours they will get access to the following link:
The long number after the equals sign is the volunteers unique identification number.