Great idea to keep kids safe if you are going to be in a crowd. Also rather than teach kids to find a policeman (hard to find when you need one) teach them to go to a lady with kids! A Mummy always knows what to do. :)
SO doing this for my kiddos someday... send Oh, the Places Youll Go by Dr. Seuss each year on the last day of school. Dont tell your kids and let them read 13 years of messages on their graduation day!