Any increase in education funding would need to come from other programs, since the state can not increase taxes without a public referendum.
At least one district, the Denver suburb of Englewood, said it would close its public schools for the day because of the teachers' action.
Some educators, including Berryhill Public Schools teacher Christina Floyd, have been at the Capitol every day since April 2. The association is asking its members to wear red - reminiscent of what teachers in Arizona have been doing in a campaign they've called #RedForEd.
This is the first day back to school for many Oklahoma students following the two-week walkout by Oklahoma teachers. Educators from other districts in Colorado are also expected to participate, though it's unclear exactly how many will join.
However, teachers said this was not enough and have asked for a $10,000 raise and additional school funding.
On Sunday, teachers in the Poudre School District were preparing for a busy Monday.
Katrina Ruff, a local Oklahoma City teacher, stood with hundreds of fellow protestors at the Capitol chanting "No funding, no future!"
Across the country, teachers have been striking and lobbying their state legislators for fair pay and labor conditions. According to the National Education Association, Colorado teachers average $US46,000 per year, and rural-based Colorado teachers can make as little as $US30,000.
Nearly thirty Oklahoma schools have announced cancellation for Wednesday's classes and admitted that if they do not see a legislative change, the protests could continue through the week.
They want the parents to know what the issues are.
The CEA estimates that teachers spend on average $656 of their own money for school supplies for students, and the organization has long argued for higher pay and better benefits for Colorado teachers.