Sometimes, a tardy slip is nothing but a reminder that a student did not make it to class on time. Especially in elementary school programs, where being tardy to school is probably not the student's fault but the parent's fault, tardy slips are used to gently remind students and parents that they must arrive on time.
Tardy slips are also used for record keeping. If a slip is handed to a student, a copy is made and sent to the office. The slips go into a student's file, so that the school has a record of how many times the student was late to school or late to a class. This way, students, parents and teachers know how often he was tardy within a given time frame.
In some schools or programs, tardy slips are used as punishments. When a student is tardy and gets a tardy slip, the slip itself is an indication of a punishment. Punishments might include a set detention, such as 15 minutes after school, or the student might have to make up the time he was tardy with the teacher, such as staying for three minutes after class if he was three minutes tardy to class. In these cases, the tardy slip itself usually lists the punishments.
Sometimes tardy slips are used as deterrents. If a student is tardy for a class or for school, that student will get a tardy slip. It will go on his record, and if he gets too many of them he will receive a punishment. However, there can also be rewards for students who do not have any tardy slips on their record. Rewards might include a field trip for students without tardies, or special privileges.