(CNN) Students of Marjory Stoneman Douglas High School return to class Monday, their first day back since organizing one of the largest youth-led protests in US history.

But these teenagers won't be returning to a normal high school experience. Instead, they'll be met with strict security measures which are intended to protect them from another mass shooting but have some students feeling as if they'll be learning in a prison.

"Going to school is really so hard, and now it's going to be so much worse," said Isabelle Robinson, a senior. "A lot of the people I've talked to are dreading going back."

Five weeks after Nikolas Cruz entered their Parkland, Florida, school and killed 17 students and faculty, MSD students led March for Our Lives rallies on March 24 in Washington and across the country. Their #NeverAgain movement has raised millions of dollars, won accolades, attracted celebrity support and pushed the issue of gun control into the national spotlight.

After the march, the students took a week off for spring break. Now they'll have to contend with a complex mix of grief over their slain classmates and excitement over their burgeoning movement.

"The march was amazing," said Daniel Bishop, a sophomore. "It was such an amazing experience to be there as a Parkland student, to experience and see all of us come together and talk about what we want to see happen."

But six weeks after the shooting and more than a week after the march, many of the students' legislative goals have not been realized.

"There's still that sense of melancholy, because what's going to happen from this?" Bishop said. "It's not like there was a magical bill that was passed that fixed all the things after the march. That didn't happen."

On top of that, Parkland students say they're apprehensive about their school's increased security measures.

"We have no sense of normalcy anymore," said Robinson, 17.

Clear backpacks and new IDs

MSD students will only be allowed to carry clear backpacks on campus and will be required to wear new student IDs at all times.

There will be an increased police presence on campus, as Gov. Rick Scott provides extra Florida Highway Patrol officers to beef up security and provide support to Broward County sheriff's deputies. Students will have limited points of entry to the school.

The school district also says it's considering whether to install metal detectors at the school's entrances. A letter from Principal Ty Thompson sent to families on Friday said that step has not been taken yet.

"It feels like being punished," Robinson told CNN. "It feels like jail, being checked every time we go to school."

When classes first resumed two weeks after the shooting , Thompson told students not to bring backpacks at all while they focused on their emotional health and not the curriculum.

Now, along with their newly donated clear backpacks, students will begin to focus on their studies again, Thompson wrote, though the school will continue to provide emotional support as necessary.

The new precautions were put in place after several security breaches last month.

A sheriff's deputy was suspended after he was found sleeping in his squad car on campus. Two students were charged with bringing weapons to school, and a third made a threat on social media. And then there was the arrest of Zachary Cruz, the adopted brother of the gunman, when he was found skateboarding on campus.

'No one feels safe'

Many students, like Robinson, aren't happy about the new security measures. She pointed out that the gunman, Nikolas Cruz, was not a student of Stoneman Douglas at the time of the shooting, so the new security measures that appear to target students are counterproductive.

"It's like putting into place all these rules that wouldn't have changed anything," Robinson said.

Some students, like senior Demitri Hoth, recognize the need for new security policies but think the clear backpacks cross a line.

"I get it," he said, but, "it feels like we are losing individualism. I understand why they are doing it, but if a person wants to bring a gun on campus, they just aren't going to put it in their backpack."

Bishop said he would support metal detectors but called the clear backpacks "an invasion of privacy." He believes the increased security measures will make students "safer," but that doesn't mean they'll be "safe."

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"I mean, no one feels safe," said Bishop. "Who feels safe in Parkland, Florida? No one."

The increased police presence has also given students of color at Stoneman Douglas a sense of unease, according to Kai Koerber, a junior. He said the school is being turned into "a police state."

"Every day, students lose more and more freedoms at MSD," Koerber said. "Students of color have become targets and white students have become suspects. We do not welcome the militarization of MSD. It is terrible to see our school lose control over the protection of their students and their families."

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In his Friday letter, Principal Thompson asked families "to be patient with these new procedures, and hopefully over time, we will be able to fine tune the process, while maintaining the safety/security."

"I realize some will want more and some will want less," Thompson added. "This continues to be a fluid process."

The new normal?

Amid the excitement and apprehension, life at Marjory Stoneman Douglas goes on.

Inevitably, students and teachers will drift back into their routines. Students will hunker down and study for their final exams while upperclassmen ask each other to prom. Seniors are receiving college acceptance letters and are just weeks from graduating.

"It was going to be a busy time anyway with college and stuff," said Robinson. "But now it's just so much worse."

Robinson, who described the weeks since the shooting as "insane," is looking forward to prom and graduation. But she knows the events will be bittersweet because of the classmates who are missing.

Meanwhile, younger students like Bishop will have to live with changed realities at their school for several more years. He thinks the activist mentality that's permeated the student body is the new normal at MSD, but he's anxious to resume classes and to put this chapter of his life behind him.

"I've been trying a lot just not to associate with Stoneman," Bishop said. "I've been trying to distance myself from the chaos. As a teenager, it's too much to handle."