Before entering the El Paso school, the 30-year-old said to the camera: "Do I look like a seventh grader? No? Cool, awesome."
Walking down the hallways, she greeted the principal, among other staff and students, admitting that she felt “really scared” about getting caught.
It wasn’t until the final class of the day that a teacher realised she was an intruder.
Following the stunt, Garcia was arrested for criminal trespassing, and tampering with government records, according to the El Paso County Sheriff’s office, as reported by CBS12.
She was later released on a $7,808 (around (£5,518) bond.
Garcia was charged on suspicion of criminal trespassing and tampering with government recordsEl Paso County Sheriff’s Office (via CBS12)
In a follow-up video, the mother explained what had motivated the bizarre move, insisting that it wasn’t to garner “views” or “likes” or to cause issues for the school.
"I didn’t do this to ruffle any feathers, I didn’t do this to out the school,” she said. “Because I was never going to say what school district or what school it was. They put that out there themselves."
She continued: "We need better security at our schools, this is what I tried to prove, and I don’t mean to be curt but I kind of feel like I proved it.
"I think the deal breaker for me was actually walking in and posing as a seventh grader. I mean I’m no spring chicken, but it wasn’t hard and I made it to all seven periods."
She also claimed that staff were more concerned with her phone being out during lessons than taking notice of her as a person.
"It was, ‘Hey, put your phone away’. I was not a name, I was not a person, I was ‘Hey put your phone away’,” she said.
She added: “This is about our children and the safety of our children,” she said. “That’s all I’m trying to do is prevent another mass shooting.”
San Elizario Schools Superintendent Jeannie Meza-Chavez defended the institution in a statement to local network KTSM.
She said: "While there was a breach in security by an individual associated as a parent with the school... we want to assure you that our security measures are being reviewed and evaluated.”