At each of our meetings we send around a sign in sheet and provide a space for members to write in their volunteer hours (since they last reported) and what event they were for. Being a PTA we keep track of hours spent on legislation and fundraising seperately. We also have a sign in sheet at all of our events so that people can just sign in then. (Dances and such the office is not even open for us to get to that book)We have found many hours were lost because people did not always sign in so.. It is part of our Event Report that is prepared after each event. (Even if it was a pizza party for 1 class) The event report notes how many people, spent how much time, doing what. This gives us a fairly accurate count.
We have a binder at the front desk and you sign-in! We are also asked to take a volunteer badge (some of us have our own and this has worked for years!! This way our school has a record (they recieve so much for volunteer hours earned because we are a charter school and rely on parents) and the PTO has a record,too!
and this has worked for years!! This way our school has a record (they recieve so much for volunteer hours earned because we are a charter school and rely on parents) and the PTO has a record,too! 
