Toby Talbot/AP Photo

Report cards are a fascinating window into what a school values. It's a given that students will get grades in the core academic subjects—reading, math, and so on—and that their absences and tardies will be recorded. But the extra skills that students are assessed for say a lot about the educational anxieties of the time and place. In the late 1800s, for example, the Los Angeles City Schools' report cards graded students in "sloyd": a form of woodworking that was supposed to prepare schoolchildren for an increasingly industrialized workforce. A Catholic school in Pennsylvania put "Christian Doctrine" at the top of its report cards for the 1916-17 school year—a clear sign of the school's primary mission.

Similarly the report-card "extras" of today reflect the concerns of the moment. A recent pilot program conducted by Cornell University researchers experimented with giving children "nutrition report cards." At a K-12 school district in rural New York state, 27 parents received weekly emails describing what their children selected at the school cafeteria.

Here's what one of these emails looks like:

The results of the program were written up in the October issue of PLOS ONE. The researchers found some evidence that students made healthier choices as a result of the report cards: Students purchased fewer cookies, for example, after the reports started going out. The study also found that the report cards encouraged parents to have conversations with their kids about nutrition. "Keeping track of what my children were purchasing at school was helpful in talking with them about making better choices about food," one of the parents in the study said.