In teaching my students responsibility, I give them each their own bathroom pass for one whole semester. Rather than have one pass that all students share (gross!), each student has their own.
I print these on card stock, and give out new ones at the beginning of the semester. When a student wants to use the restroom, I simply write the date on the line - they get 8 total uses.
This is uploaded as a word doc so you can change it to your name and classroom number.
I also like to collect these at the end of the semester and offer rewards for students who 1) still have them, and 2) have not had to use classroom time for restroom usage. This method motivates a lot of students to really think twice about leaving the classroom!