Simple. Everybody had on clothes that were't suitable for the school dress code on their bodies. They could have just gotten back from swimming. The elderly couple saw this and decided to call the school because that is what elderly couples do.
Hmm?
Here's another that could work. March 20, a Sunday, was the day the students went to celebrate mother's day. March 21 is Mother's day. So, the students decided to go to the childless couple who runs the Miller Shop and spend time with Mrs Miller for a couple of hours. During their time there, one of the students rips their uniform accidentally. They all go back to school the day after, and Mr Ingel, Ms Miller's brother saw all this, and wanted to personally thank the students involved, even if it meant truancy, and wanted to offer the student who ripped his uniform a new uniform.
Edited 7/27/2015 05:16:33