At our elementary Open House the kids and parents visit the classroom together. The teachers don't have time slots for each family, they are just in the classroom and will chat with the students and their parents as they come in. If the parents need private time with the teacher she can then set up something for them. It's much more informal than your event.
I think you are on the right track with your plan for organizing volunteers and a2's idea of asking the support staff to help is a great one. Often times I don't think parents and students even visit with these teachers, so it would be a great chance for at least the students to get to know them.
Instead of sign in/out, you could just use a number system where when the parents drop off the child(ren) you write a number on the back of each person's hand. When they pick up you would just have someone verify that everyone has the same number on their hand. Not perfect, but much simpler.
As for bathroom breaks, are you letting kids just go as they need to? If so, change to a situation where every 15 minutes you call bathroom break and anyone who has to go lines up with designated volunteers and heads out. This is similar to the way the kids will have it during the school day, so they might as well get used to it early.
I think the kids should absolutely come to BTS night! They are the ones coming "Back to School"!! I think you're on the right track with your volunteers, asking them to work the 30 minute shift either before or after their time with their child's teacher. At our school, we also ask our support staff to help out (guidence counselor, media specialist, lunch room monitors) because we usually have a shortage of parent volunteers and they are more than happy to help out. I think the lunch room is probably your best bet as far as child "containment" (LOL)...if offers a quieter enviroment for parents to find their children afterwards. Again, I think you're on the right track as far as offering several different activities for the different age groups. Good Luck!
We have a BTS for the last 4 years. At this event we have the kids come to a common area and the parents go to the classrooms. Then parents come back to get the children and they go visit the classroom. So, first we had them go to the playground, which was great the problems we had --we had a sign in/out this was too congestive. Then parents had a hard time finding the kids(running on the playground) not enough volunteers.
Then we moved them into the lunch room (3rd year) to watch cartoons on the big screen. This worked out great for the younger kids but the older kids (3rd and 4th graders) were bored.
Plus we have the drama of the bathroom visits--and playing in the hallways.
Did I mention not enough volunteers.
This year we have thought of just playing games and having cartoons play on just two tvs and have tables set up so the older kids can just socialize.
The volunteers are hard because the teachers only have 30 minutes slots but that doesn't include taking the child back so many of our parents have children of many grades so they can't be in two places at once. I think I have came up with a little solution--if your time is 6-6:30 then I'm asking them to come and work the 5:30-6:00 shift and so forth. This may help with the teachers running over and so forth.
I would like to know what others do for BTS night?
We also feed the teachers dinner.
My officers are tried of this event and think the children should stay home.
The principal feels this helps the children for the first day of school.