Thomson's first appointment was to the school department where he taught arithmetic, geography, and bookkeeping for a year before moving to the college department where he became professor of mathematics.
Thomson's unang appointment ay sa departamento ng paaralan kung saan siya nagtuturo arithmetic, heograpiya, at bookkeeping para sa isang taon bago lumipat sa kolehiyo department kung saan siya ay naging propesor ng matematika.