Erin Castillo, an english teacher at John F. Kennedy High School in Freemont, Calif., created a mental health check-in chart for her students. Now, teachers all over the world are making their own ...

The Global Assessment of Functioning, or GAF, scale is used to rate how serious a mental illness may be. It measures how much a person's symptoms affect their day-to-day life on a scale of 0 to 100.