Parents are going to love this hack. Since a lot of washers and dryers out there feature an enamel finish, you can use a dry-erase marker to leave notes or reminders for anyone who has trouble remembering to separate their clothes. Actually, you could use this hack to write just about anything that you want. You can draw a calendar to keep track of laundry or just write a little fun quote to make washing clothes a bit more bearable.
However, this one comes with a caveat. Obviously, if your washer and dryer don't have enamel finishes then proceed with care. A glass top should still work but you might want to consider switching up your marker color.