NEW YORK (CBSNewYork) — Some major milestones have been reached on the road to reopening.

In New York City Monday, high school students returned to the classroom for the first time since last November.

READ MORE: Mayor Bill De Blasio Says New CDC Guidelines Will Allow 'A Substantial Number Of Students' To Return To Classrooms

Also, indoor fitness classes resumed in the city, and, statewide, gathering limits were expanded.

On the vaccine front, Gov. Andrew Cuomo lowered the eligibility age to 50 in New York, and AstraZeneca announced the results of U.S. trials show its vaccine is effective and will apply for emergency use from the Food and Drug Administration within a few weeks.

As CBS2’s Hazel Sanchez reports, it has been a long four months for New York City high school students. Those who have chosen to return were excited to be reunited with their classmates and teachers.

It wasn’t exactly a normal day for students returning to in-person learning at Bronx School for Law Government and Justice. They were greeted at the door by Mayor Bill de Blasio and new Schools Chancellor Meisha Ross Porter.

Across the five boroughs, 488 high school reopened Monday. About half are offering five days of in-person learning to all or most of their students. Testing consent and temperature checks are required to get back in the classroom.

Many students were tired of being stuck at home.

“I missed talking to my teachers and my friends, and also obviously participating in school,” said freshman Zira Nunez.

“Most kids are ready to, you know, all of us, to get back to normal,” said senior Piper Rogers.

WATCH: Mayor, Schools Chancellor Discuss Reopening Of NYC High Schools 

“For me, it’s been calm, but I know for other people, it’s been like, ‘Oh my God, what am I going to wear, where am I going to go, how’s my hair going to look?'” Zira Nunez told CBS2’s Kevin Rincon.

It was like the first day of school all over again.

“I missed talking to my teachers and my friends, and also obviously participating in school,” Nunez added.

Sophomore Alexander Almonte said after a while, the screen time got old and he missed being inside the classroom.

“The hardest part was just not having that in-person chemistry,” he said. “That good feeling when you’re brainstorming with your teacher, asking questions, giving answers and feedback and all that stuff.”

READ MORE: Remote Learning Still A Struggle For Students, Parents 1 Year Since New York City Schools Shut Down

Some students at Talent Unlimited Performing Arts High School on the Upper East Side say it was a struggle learning from home for more than four months. But coming back wasn’t easy for everyone either.

“It was kind of awkward. Like, not being used to seeing everyone on the screens and, like, coming in person. Especially playing music and not playing by yourself,” said freshman Zoey Pena.

“I was kind of nervous at first because I was like sitting and I was just like, I don’t know if this is gonna work. I’m kind of scared,” said sophomore Omari Williams.

In Hell’s Kitchen, teachers reassured students they’ll do everything they can to keep everyone safe.

“We have disinfectors in every classroom. We have masks, we have extensive amounts of PPE. So we feel we’re ready,” a teacher named Rebecca said.

“We are very excited to do the one thing we’re meant to do, and that’s teach kids in person,” said teacher Kurt Schneider.

Students are just hoping everyone will stay healthy to keep in-person learning consistent.

“When I’m at home, I do, I’m gonna be honest, I do procrastinate at work.  But when I’m at school, it’s like a different mindset,” said sophomore Quintin Anderson.

“If the school does manage to stay open, I think it’s gonna be better for the long run for students learning,” said sophomore Danny Gonzales.

This came as the mayor and schools chancellor announced the next opt-in period opens Wednesday, March 24, through April 7.

“We intend to have the opt-in period and then honor those who want to opt back in, bring those kids back during the month of April, by the end of April for 3k, pre-k, elementary school and District 75 special education up through the elementary level,” de Blasio said. “We still have more work to do for middle and high school, we’re still not sure about those timelines. But as I said, the opt-in will include middle and high school students, so we know what their intentions are.”

“What this morning reminded me of is why it’s important to open our doors and why that guidance from the CDC is so critical for what we need to do for students across New York City,” Porter added. “It was an even more critical reminder of why we need to open the opt-in window now, so that schools can start planning for the opportunity to welcome more students in.”

Michael Mulgrew, head of the teacher’s union, said in-person learning benefits everyone.

“It’s not ideal teaching anyone remotely. The teachers really do not enjoy it,” he said.

Mulgrew was asked about the new CDC guidelines, that reduce six-feet social distancing requirements to three feet. He said they’re complicated, since teachers still need to be six feet apart.

MORE NEWS: Exclusive Interview With Schools Chancellor Meisha Ross Porter During Her First Day On The Job

CBS2’s Kevin Rincon contributed to this report.