Marybeth Gasman, a University of Pennsylvania professor who lives in Old City, didn't set out to conduct a social experiment on Saturday when she put on a Black Lives Matter T-shirt and headed to Cherry Hill.

It just turned out that way.

The shirt she wore that day was an old one that Gasman had ordered for her staff at Penn's Center for Minority Serving Institutions.

As she dressed for her mother-daughter day of brunch, shopping, and a movie, weighing heavily on her mind was President Trump's racist tweet questioning the intelligence of both NBA superstar LeBron James and CNN's Don Lemon. It was also former President Barack Obama's 57th birthday, so she decided to put on her Black Lives Matter shirt and promptly forgot about it. Until she entered a Target store across Route 38 from Cherry Hill Mall and noticed a white female shopper shooting her a dirty look.

"Her eyes were sort of bulging out, and she scoffed at me," Gasman told me.

At first, it confused her. Then the education professor — she's the Judy and Howard Berkowitz Professor of Education in Penn's Graduate School of Education and also directs the Penn Center for Minority Serving Institutions, making her a leading authority on historically black colleges and universities — remembered the shirt she was wearing.

Gasman continued shopping. As she waited for her daughter to exit a dressing room, an older black woman approached and said, "I love your T-shirt." The stranger walked away, only to return and say, "I want you to know that your life matters to me as well." She also took Gasman's photo.

Although most people didn't seem to notice what Gasman was wearing, she attracted the occasional eye roll or smile. When she was at the theater, an African American ticket seller flashed her a smile and said, "Nice shirt." But an older white male rolled his eyes and shot her a dirty look. A black woman in a parking lot with two young boys in tow smiled.

Once back home, Gasman posted about her experience on Facebook, writing: "How can anyone not agree that Black Lives Matter?"

It sparked quite the discussion, with nearly 200 comments and 40 people sharing it.

Truth be told, I've been Facebook-stalking Gasman ever since I heard her speak in 2017 at a WHYY event about being raised in rural Michigan by a racist father who despised African Americans and blamed them for his failings in life. He was an unhappy man who eventually had a change of heart after going into a nursing home and getting a black roommate, a Mr. Johnson, with whom he bonded over televised sports. Before then, he hadn't known any black people. After hearing Gasman speak so eloquently about the roots of racism, I've been in fangirl mode.

I reached out to her earlier this week and asked for a meeting. It was really an excuse to sit and explore with this brilliant woman why even the mention of  Black Lives Matter is still such a flash point. I've wasted more time than I care to admit trying to explain to folks how the grassroots movement that began in 2012 after the death of Trayvon Martin, the unarmed Florida teenager killed by a neighborhood vigilante, is against police brutality and systemic racism — not against white people.

"I think what people don't understand is that saying that Black Lives Matter doesn't mean that other lives don't matter," Gasman said Wednesday morning over coffee at a Starbucks at 39th and Walnut. "What it means is that at this moment in time, African Americans are experiencing escalated racism, escalated hate."

The usual comeback in my experience is, "Why can't you just say all lives matter?"

"I'm not seeing white folks being treated the same way as black people in society," Gasman told me. "I'm not seeing people call the police on white folks for sitting in a loungefor being at a swimming pool for being at a Starbucks. We're not seeing that. I didn't see a white person treated the way Sandra Bland was by the police in Texas. I haven't seen white people being treated that way."

Gasman, an author of 25 books dealing with race, equity, and higher education, said that too often white people resist acknowledging racial disparities out of fear that "black people are going to get something that I don't have" or "they are going to somehow matter more."

"That's not what this is about at all," she said. "It's about the idea that we need to remember that black people have value."

We shouldn't need a T-shirt to remind us of that.