The service as teacher for Mr. Morgan (I still give teachers the same respect) may have been in several school Districts. Individual districts would have records, but due to the time he served, that was before Washington became a State in 1889. So, if records exist, they would be in archives.

I would first start with the Public Disclosure Office for the Superintendent of Public Instruction. They may have accreditation files, or work service records. Call them instead of just sending in a form. Ask your question about potential records:
http://www.k12.wa.us/publicrecordsrequest/

They may indicate any such records would be in the Archives of the State of Washington, held by the Secretary of State:
http://www.secstate.wa.gov/archives/archives_state.aspx

Ron Bestrom