When the pandemic began more than a year ago, the country changed overnight. For teens everywhere, there were a lot of unexpected adjustments -- schools closed, extracurricular activities were non-existent and friendships were reduced to Zoom hangouts and virtual TikTok challenges.

The uncertainty of when or if school would resume in person, and then the reality that for many teens, an entire school year would be lost to the pandemic triggered feelings of anxiety, isolation and depression, experts said.

“For the extrovert kids who were used to being out and about, the pandemic brought a lot of anxiety and depression because of decreased social interaction," Dr. Chioma Iheagwara, division chief of child and adolescent psychiatry at Belmont Behavioral Health System, told "Good Morning America."

On the other hand, "some kids who were struggling or being bullied in school started to thrive when removed from the school environment," Iheagwara said. "Now they might be fearful about going back to school because the bullying could resume. The pandemic has been challenging for all kids, so how to support each teen really depends on where they started."

5 tips to help support teens' transition back to in-school environment

1. Re-establish routines and create a sense of normalcy

Creating routines can help minimize anxiety as teens start the school year.

"Normalize life as much as possible within the confines of dealing with the pandemic,” Iheagwara said. "Normalcy right now might be wearing a mask. Doing activities – enjoying life whenever possible, but that’s normalcy.”

According to the Centers for Disease Control and Prevention, re-establishing routines with sleep, family meals and other social activities, while helping teens to take personal responsibility to protect themselves and others can also help.

2. Look out for changes from baseline

Parents should keep an eye out for new eating habits -- eating too much or too little -- as well as new social habits or increased sensitivity. All of these could be signs of what mental health experts call "maladaptive" coping strategies, which are short-term attempts to reduce negative symptoms, without addressing or resolving those symptoms.

"If you know your child has anxiety, you know they are still going to have some level of anxiety and you prepare for that. But your teen who now looks more anxious, who’s now more isolated or irritable – if there’s a significant shift from the child that you know, something’s going on there and needs to be explored," Iheagwara said.

3. Make a plan as a family.

With different rules around mask wearing from school to school, it’s important to know what’s happening in your teen’s school or school system.

Have "real honest and earnest conversations about what’s beneficial for you as a family -- you might decide that means wearing masks no matter what the local guidelines.” said Iheagwara. "Discuss with your teen what the school expectations are around infection control and then what the household policies will be, including how you want to handle any illnesses that pop up in the family."

4. Check in.

The pandemic has been a constantly changing and confusing landscape for over a year. It's important to create safe spaces for teens to feel all the emotions associated with this experience. The first day of school might look very different a week or a month later, so checking in regularly on how a teen is handling the transition back to in-person learning will be important.

Pediatricians say parents can play an important role in setting the tone in the household. Expressing extreme doom or fear can affect your teen, but together, identifying self-care activities and productive ways to process any stress or anxiety can go a long way. “Keeping a normal routine and keeping lines of communication open between parents and teens is the most important thing," Iheagwara said.

5. Get extra support.

Families should reach out to their pediatrician, or a mental health provider if available.

"School counselors and school behavioral health counselors can also offer support or additional resources – for emergencies, many states have crisis response centers, as an alternative to a traditional hospital emergency departments,” Iheagwara said.

There are also apps and online resources for teens at the ready that can be beneficial.

Companies like Limbix, Akili and Pear Therapeutics have digital products offering support for several adolescent mental health concerns.

The American Academy of Child and Adolescent Psychiatry offers several resources, the CDC and AAP also have online resources for teens and families.

Chidimma J. Acholonu, MD MPH is a Pediatric Resident Physician at the University of Chicago. She is a medical contributor for ABC News Medical Unit.