Keeping track of bathroom breaks

This year, I've been playing around with different ways of keeping track of which students are in the restroom. I have the Kindergarteners for 25 minutes and my 1st-5th graders for 50 minutes this year. Fifty minutes with 1st grade can be a long time to go without using the restroom! My first grade teachers are great about having students go before specials, but still...I've seen students have accidents before, so although I sometimes make them wait a little bit (if we are in the middle of an assessment, for example, or music is almost over), I do give them an opportunity to go if they really need to.
You all know what it's like, though, when one first grader asks. Soon, half of the students have their hands raised (or their fingers crossed, as my students do) showing they need to go to the bathroom. My general rule is no more than 2 in the bathroom at the same time (and I've explained many times how little time I get with them and how much I need them all present in music). I tried having students write their names on a list earlier this year, but the list filled up after a couple days, and then I had to print out new ones, and I wasn't great about always having students sign the list.
I saw the P.E. teacher at my school do something very cool...he put numbers on basketballs, put magnets on the back, attached them to his magnetic wall, and then students were responsible for moving their number when they left for the restroom and when they came back. Love it! (By the way, if you have a PE teacher at your school who likes to shop on TpT or who wants some new ideas, my PE teacher's store is up and running...lots of fun stuff!)
I wanted to find something musical instead of basketballs, but I couldn't find anything, so I bought trees and fruit instead. I found these at Michaels:

After buying enough wooden pieces for the students in my class, I also bought a sharpie and magnets, shown below:

Besides those materials, I just needed a glue gun. I first put the numbers on all of the wooden pieces, then added a dab of glue with the glue gun to the back of a magnet, then put the magnet onto the back of the wooden piece and held it there for 10 seconds. (To be honest, my 10-year-old was a HUGE help with this! She glued while I wrote numbers!)

This is what the back of the magnets looked like. I let them dry for a little bit before bagging them up and taking them to school.

Once I took them to school, I printed  out signs that said "Restroom," "Nurse," and "Here," then put all the magnets under "Here."

Then at the beginning of all the next classes, I explained that if students needed to go to the restroom, they would first have to ask me (by crossing their fingers), then put their number under "restroom," then when they get back, they have to put their number back under "here." In the picture below, student #17 was in the restroom.

This board is in my direct line of sight, so it is a GREAT visual to just look and see how many students are in the restroom. The students are beginning to understand that if there are two magnets under "restroom," they might as well just wait to ask to use the restroom! Another bonus to this is being able to tell the teacher about any students who are at the nurse or still in the restroom at the end of class...or better yet, if there is a fire drill or any other kind of drill, you can easily tell who is missing!

Feel free to comment below if you have any other ways of keeping track of students in the restroom, and have a great week!