I just reread what I wrote. My wording definitely needed to have been more considerate! I apologize. You didn't deserve that. I do think that there is not enough structure in place, but that's why you are here! You deserve our support and understanding. As to what procedures you need to teach... you just named one. They need to learn not to go while you are teaching whole group. I am assuming your lessons are not more than 10-15 minutes long at one stretch. You need to teach them when is a good time to go and when it isn't. While it would take their bodies time to get used to that (and think ahead) and it doesn't guarantee that someone won't need to go in the middle of a lesson, over time and with reinforcement, it is an effective rule. Secondly they need to learn time management when they go to the bathroom. You need some kind of rule and procedure for this. Kids will take advantage of both of these areas if you let them because they are both social creatures and developmentally time is not an issue especially since playing is so much more tempting. But kids can be taught to follow procedures to help them learn both of these areas. Many of the suggestions here are really good and can be used in conjunction with good solid procedures in order to reinforce them and transition them into a more structured plan. (I have had a variety of bathroom settings. The closest I've come to what your situation is one scheduled break and bathroom as needed--bathroom semi across the hall).