Mícheál Marsh instructed high school mathematics at Culver City High School in Culver City California for 27 years. He began his career in education in 1986 as a student intern for Project T.I.M.E. (Teachers Improving Mathematics Education), a Tri-Counties Mathematics Project (TCMP) that worked with primary through secondary schools around the University of California at Santa Barbara.

Mícheál obtained his B.A. in 1987 in mathematics from UCSB along with his teaching credentials (1988) M.A. (1992) in Math Assessment. He began teaching in 1988 at Fillmore Middle School in Fillmore California. In 1992 he came to Culver City High School where he has remained in various positions from department chairman to Teacher on Special Assignment (TOSA) in the area of assessment and technology.

He has taught CPM since 1993 and served as a teacher leader, contributing editor, regional coordinator, and technology director for CPM. He obtained an M.A. from California State University Northridge (CSUN) in Educational Leadership and an administrative credential in 2011. Currently, he is a CPM Regional Professional Learning Coordinator for California.