
My must have, since I am still a substitute teacher, is very detailed lesson plans! In a huge district with 7 elementary schools, it's very common that I walk into a room without detailed lesson plans.
The more details the better! I know how important structure is and it's difficult to keep that structure when detailed plans are not given. So I am very thankful for this must have!

You don't understand how nice it is to work in rooms that are organized, ready and detailed! Some days I walk away feeling like I wasted a day trying to figure out how to run certain activities, and I get tired of hearing "No we don't!" and "Yes we do!".
Some classes are better at "Do I look like Mrs. So-and-so? Is it okay if I do things a little differently?" However, some classes cannot handle any change at all.
So my must have, is detailed and organized lessons when I walk in!