In one school district in Colorado, teachers truly are walking out this week to join the massive rallies at the State Capitol.

Rally organizers weren't expecting a large contingent from Aurora Public Schools because contracts prohibit teachers from leaving en masse. Even so, Aurora said they're canceling classes Friday, citing a teacher shortage.

9NEWS has learned Aurora teachers are walking out of school without pay; this appears to be the only school district where this is the case.

An email from Superintendent Rico Munn to staff says the leave-without-pay day isn't being approved, or denied for teachers, but it should be reported to administrators. A teacher who calls out sick may be asked to show a doctor's note.

The email says the Colorado Education Association, the state's largest teacher's union, has encouraged districts to take whatever action possible ahead of the rallies, which is consistent with contracts. Munn wrote that this is what the district is doing, and even he does not have the authority to change the contractual limitations.

The superintendent apologized to teachers for the confusion.

Aurora Public Schools did not respond to several requests for comment from 9NEWS.

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