A simple tweet welcoming a Toronto-area high school principal to her new post has become the subject of a national news story this week, thanks to one detail in a photo that's pretty easy to miss upon first glance.

Cardinal Ambrozic Catholic Secondary School in Brampton published the tweet in question on September 3 — the first day back to school for most Ontario students.

"Cardinal Ambrozic extends a warm welcome to Ms. Battaglini, our new Principal," it read. "We are excited to have her join our community. Looking forward to a fantastic year with her leadership."

Cardinal Ambrozic extends a warm welcome to Ms. Battaglini, our new Principal. We are excited to have her join our community. Looking forward to a fantastic year with her leadership. pic.twitter.com/MoB5nRpkRr

— CardinalAmbrozic CSS (@CardinalAmbro) September 3, 2019

Battaglini is pictured with the tweet smiling behind her new desk, surrounded by paper and office supplies.

Upon closer inspection, a book can be seen in the foreground of the photo bearing the title "The Guide for White Women Who Teach Black Boys."

Yeah. That didn't go over well on Twitter.

?????????????? pic.twitter.com/lMWW6te6Wc

— ひ (@glogangboog) September 5, 2019

As soon as someone noticed the book and highlighted its existence in the photo, people from all over the country started jumping into the Twitter thread with accusations of racism.

"If you need to be reading this book then you are in the wrong profession!" wrote one critic. "This is absolutely ridiculous!"

"I think someone writing a book about white people teaching black kids is f'd," commented someone else. "I don't see one about black teachers teaching white kids... This is racist as hell."

The truly sad part is that you think you don't need assistance or guidance on teaching white boys. If you were any kind of parent you would know that colour has absolutely NOTHING to do with how they act. They're teenagers! They were meant to be challenging. Burn that book!

— Mary Anne Head (@CAKED_INK) September 6, 2019

Others immediately jumped to Battaglini's defence, noting that the book is meant as an educational guide and teaching aid.

"This lady is going out of her way to utilize all resources she can possibly get ahold of in order to make a positive impact in her black students' lives," wrote one Twitter user user in response to the controversy. "I cannot even fathom how anyone views this negatively. I am proud to know our youth is in good hands."

I admire your dedication to your students and for challenging and educating yourself on issues related to systemic racism!" wrote another. "This book is attempting to break down barriers, not create them!"

You guys are too quick to judge. If you actually took the time to do your research about the book you would realize that she just wants to educate herself. Since you are too lazy to do your research, I’ve done it for you. Your welcome. pic.twitter.com/WhvDs7BU8V

— Lynn-Asia (@lynnasiah) September 5, 2019

As for the principal's employer, The Dufferin-Peel Catholic District School Board, they've got her back.

The school board says that, while the book may have a "provocative title," it is actually "a helpful resource on tackling racial and cultural oppression in education."

As the CBC notes, the book was written in 2017 by researchers to help teachers — the majority of which are white women in the U.S. —improve academic outcomes for black students by creating supportive and engaging learning environments.