I think this is a must-read for all teachers.

Erin Castillo, an educator at John F. Kennedy High School in Freemont, California, created a mental health check-in chart for her students.

Now, she's inspiring teachers around the globe to make their own versions of the chart for their classrooms.

Students are encouraged to grab a post-it, write their name on the back and place it next to the statement on the chart that best matches their feelings for the day.

The options are, "I'm great", "I'm okay," "I'm meh," "I'm struggling," "I'm having a hard time and wouldn't mind a check in" or "I'm in a really dark place."

The last two statements merit a check-in with Castillo and a follow-up conversation with the counselor or the school psychologist on campus.

"I never expected it to get beyond my following," Castillo told Good Morning America of her chart, which was originally posted on her Instagram  page.

"I've had a lot of students in the last five years of my career that have struggled with self-confidence, self-doubt, image, had suicidal thoughts, attempted suicide and, after seeing all that, I've been making it a theme in my classroom and trying to check in with them," she added.