This website has a helpful list of must-have procedures to go over with students on the first few days of school. The list is thorough and it's important to teach these procedures for an efficient classroom. First week of school
19 Ridiculously Simple DIYs Every Elementary School Teacher Should Know
(I love these ideas. Great for summertime ideas to help keep kids learning.) 19 Ridiculously Simple DIYs Every Elementary School Teacher Should Know (great modifiable ideas for piano lessons and homeschool too!
Attendance as they walk in! A quick get to know you/math (counting and graphing) activity. Later in the year students can generate the questions and write them. Place on light colored paper, laminate, and questions can be added with white board marker.