BANGOR, Maine — Kate Dickerson resigned from the Bangor school committee Tuesday night, citing what she called a “culture of passivity” and absence of debate on the committee.

Dickerson, who was elected to the committee in November 2010, read a statement decrying what she described as “efforts to stifle free expression and limit open discussion of pertinent issues” and “the abdication of true leadership on the part of the committee.”

After reading her resignation letter, Dickerson quickly stood up, gathered her things and left the room. Her term was set to expire in November 2013.

Her statement and departure were met with silence. Superintendent Betsy Webb said the resignation was entirely unexpected.

“Well, I’m sorry, I’m a little taken aback and not quite sure how to proceed,” chairwoman Phyllis Guerette said. The meeting continued, with discussion of a new portable classroom, committee updates and second readings of several policies.

“I have not been shy in asking questions, soliciting ideas and input from the community, researching promising initiatives and promoting vigorous debate and productive discussion to advance our mission,” Dickerson said during her statement. “Unfortunately, such is not the norm for the Bangor school committee.”

In her announcement, Dickerson cited several incidents that influenced her decision to resign.

During her first meeting as a committee member, Dickerson brought her laptop so she could take notes and reference sources online as needed, she said.

The next day, Guerrette called her to ask why she was using the computer and stated that “people are wondering why you’re hiding behind it, and if you are even paying attention to what’s going on,” according to Dickerson.

In June, a panel rejected Dickerson’s attempt to start an alumni endowment to fund school sports and clubs, with Dickerson casting the lone vote in favor. Members of the committee and Webb said at the time that Friends of Cameron Stadium, a nonprofit group formed in 2010, already was trying to raise $7 million to renovate Cameron Stadium and planned to ask alumni to kick in.

Dickerson’s attempt in April 2011 to form an ad hoc committee also fell flat, and she was the lone dissenting vote when the committee voted to cut $130,000 from the 2011-12 school budget in May 2011, though other members of the committee said they were disheartened by the Bangor City Council’s recommended cuts.

“My public inquiries, challenges and proposals have been greeted with such a lack of professionalism — and what can only be described as outright bullying — that I’ve lost faith in the system’s integrity,” Dickerson said.

In the latest incident, during the Sept. 27 school committee meeting, Guerette said she “inadvertently” had heard that Dickerson was planning a large-scale event and asked Dickerson to inform the board.

Dickerson declined to give details, saying, “I can’t right now, actually, sorry.”

Guerette, who had obtained documents about the event, proceeded to hand out sheets of paper to the other committee members. The papers included draft calendars of events for a science festival to take place sometime in 2014.

Guerrette questioned why Dickerson would be planning an event without consulting Webb or the committee. She argued that the event would require use of Bangor school facilities and that the council should have been made aware that Dickerson was considering the idea.

“That’s very concerning to me,” Guerette said at the September meeting.

Dickerson said she told people she spoke with that she was not representing anyone but herself. Others on the committee argued that because she was a committee member, people would assume the committee was involved.

Dickerson chided Guerette for bringing up the potential event during the public meeting. She said the plan was part of a personal project that was in its infancy and wasn’t ready to be made public or brought before the committee. She expressed concerns that Guerette had compromised the future of the event by bringing it up.

“I find it stunning that you find it difficult to believe that I might have some ideas that are not fully fleshed and not ready to be formed with the public, which you have just chosen to do without speaking to me at all,” Dickerson said to Guerette at the September meeting.

Later, Dickerson sent an email to Guerette asking for an apology.

“I’m sorry if you took offense at my remarks, I thought I was giving you an opportunity to explain this exciting project and giving you the opportunity to get on the right path as far as following the proper protocol and procedures,” Guerette said at Tuesday night’s meeting. She went on to add that she felt the festival could be great for the community and said the committee might have been happy to get involved.

Dickerson followed up on Guerette’s comments by reading her resignation statement.

Committee members Warren Caruso and Christine Szal said after Dickerson left that they have never felt their opinions, suggestions or questions were unwelcome in meetings or in conversations with Guerette and Webb. Szal said she believed Dickerson had “overstepped her bounds.”

Dickerson said the Sept. 27 discussion contributed to her decision to leave the committee, but that it was just one of many instances of “derision and intimidation.”

“If it wasn’t this, I think there would be something else,” Dickerson said. “It’s a continuous pattern that’s been going on for a long time.”

Webb said after Tuesday’s meeting that she would have to double-check to see what the procedure is for filling a vacancy on the school committee. Because Dickerson had more than a year remaining on her term, the city may need to hold a special election, the superintendent said.

“I’m really sad about this whole thing,” Dickerson said Tuesday about her decision to resign. “I think it’s unfortunate that it’s gotten to this level. I hope that this fosters a conversation within our community.”