This is a fun game that you can use to keep kids guessing for a long time. You start off by telling kids that there is a special place behind the Green Glass Door and only certain items can go back there. If they can figure out what can go behind the Green Glass Door, they can be part of the club – but they can never tell anyone the answer. Then you further confuse them by giving them a list of things that can or cannot go behind the green glass door such as: There are floods but no water, pizza with no sauce, schools but no teachers, trees but no leaves. The trick is items can only go behind the Green Glass Door that have a double letter in them. Hence the name grEEn glaSS dOOr. It will drive kids crazy until they can be part of the club.