Grade papers. Assign homework. Prepare lesson plan. Make Oreo McFlurry. For some teachers, that’s a real-life schedule one or two days a year, and not because they need a part-time gig to supplement their day jobs. Instead, they’re participants in “McTeacher’s Nights,” in which they “work” at a local McDonald’s for a few hours in return for a portion of that evening’s sales being donated to their schools…