How do you become a teacher? College Major In Education:  Check out the list of Missouri Teacher Education Institutions which offer teacher certification.  A major in Mathematics Education or Science Education can often get you certified in just four years. Substitute Teaching:  The Missouri Department of Elementary and Secondary Education requires at least 60 hours of college credit and a background check before one can become a substitute.  Some school districts may require more.  Check with the superintendent's office for more information. A listing of Missouri school district's websites is available at: DESE.