Hi,
We have been using Google groups for over an year now. I have over 500 emails on our announcement group, which is basically a listserve. After the fires last year, my group was just set up and I did not have many perimeters on it. It allowed others to reply to our messages, but things got a little out of hand, people started talking about where to take their kids since they were in school and how bored they were? This prompted us to create a 2nd group, which was for discussions and / or non school related information. The announcement group is not set to send messages and only those that are set up as a manager or owner of the groups can see a reply and response to that message. Key thing, be careful when replying for you could reply to the entire group. This group is stricly for announcements that are pertaining to school events.
We since have over 50 google groups. Each classroom has their own group to use for a communication tool, each program or event team has their own group. This allows that specific group to communicate amongst themselves vs. the entire school. There is no limit to how many groups you set up, but I do recall there is a limit of how many you can set up in a day or week? maybe 20? Also as mentioned in earlier emails, it's much easier to simply "add" vs. invite your people, but they will stop you for review if you add to many at once. I usually add about 7 at a time. But can add up to I think 40 per day? The way around this, if you have others that can assist you, add them first, set them up as managers or owners and then they can start added to your group. By inviting, you will then have to wait for those to accept the invite before they receive an email.
The one advantage of Google vs. Yahoo, is that they have Google Doc's. We created last year a master Doc. It has all the information of our students. Student name, classroom, grade level, siblings?, parents names, address, phone, email, etc... We were passing around a flash drive and it only allowed us one at a time to insert our update info. With Google Documents, you can create a doc, file share and collaborate together. you can use this doc to make a column that indicates if the email address has been added to the google group and then more than one person at a time, (10 - 20? ) can add names. It's real time so you can see what is happening.
This is also a great tool, for your classrooms, you can create a sign up sheet that will link to one of your pages on a class group, it will allow the parents in the class to update and see real time the needs so more than one person doesn't sign up for the same thing, because it was missed in the delay of an email? Yahoo does not offer the collaborating of doc's. Google continues to expand, offering more and more. It's certainly not perfect, the calendar function doesn't link to the groups yet, but I suspect in time it will. That too, just log in and share the calendar with whom you like and they can access or add events.
Please note, that all of our groups that we have set up, we did keep them private. We did not want anyone to be able to do a search and access information. It's just a better safety precaution.
Hope that helps.