Oklahoma City, Oklahoma(CNN) This is a battle that could shutter some classrooms indefinitely.

Hundreds of Oklahoma teachers filled the state Capitol for a second day Tuesday, demanding an additional $150 million in school funding and increased raises for themselves and support staff.

Their walkout comes days after the state approved some raises and school funding -- but only a fraction of what the teachers' union demanded.

So despite school cancellations and even the risk of discipline from some districts, teachers say they won't budge.

"We will hold the line until hell freezes over, and then we will be here on ice skates," Muskogee High School teacher Diane Walker said. "We love our kids."

Crumbling textbooks and begging for paper

For those who don't understand why schools need more funding, the mother of an Oklahoma eighth-grader shared a photo of her daughter's dilapidated history book, which says George W. Bush is the current president.

Several students told CNN their classrooms run out of basic supplies such as paper.

"Last year, my English teacher, when we ran low on paper, she had to get some from church," said Carlos Servano, a 17-year-old senior at Yukon High School. "That's crazy."

While some teachers have said the $50 million increase in school funding approved last week is a good start, it's not nearly enough to get classrooms in adequate shape.

Alicia Priest, president of the Oklahoma Education Association, said the $50 million "will buy less than one textbook per student in Oklahoma."

Politicians stand firm

As they packed all four floors of the Capitol rotunda on Tuesday, teachers shouted a message to legislators: "Fund the future!"

Jonathan Moy, a Yukon High School teacher who works six jobs to make ends meet, captured footage of the scene. Some held signs reading, "Straight Outta Funding."

But lawmakers have given no indication they'll meet the teachers' full demands, saying they just passed historic funding for teachers, support staff and schools last week.

"This legislation will provide an average teacher pay raise of $6,000 to our teachers. That is a 16 percent average pay increase for teachers," Gov. Mary Fallin said in a statement.

She added that the $50 million allocated for school funding marks a 19.74% increase.

"Just like Oklahoma families, we are only able to do what our budget allows," Fallin said. "We must be responsible not to neglect other areas of need in the state, such as corrections and health and human services, as we continue to consider additional educational funding measures."

On Tuesday, Fallin signed into law a $2.9 billion public schools funding measure that had been approved by lawmakers, according to a news release from her office. The measure takes effect July 1, the start of the state's 2019 fiscal year.

But Priest said the funding still falls short of fixing problems such as "classrooms with more students than desks, duct-taped text books, and schools that are only heated to 60 degrees."

And so the standoff continues.

Tulsa Public Schools said its schools will be closed Wednesday due to the teacher walkout.

Moy said the impasse between lawmakers and educators might spell the end of his teaching career.

"The more I listen to our legislators," he said, "the more it feels like my days in the classroom may be over."