In the present paper, we develop a teaching methodology for economic theory. The main contribution of this paper relies on combining the interactive characteristics of spreadsheet programs such as Excel and Unicode plain-text linear format for mathematical expressions. The advantage of Unicode standard rests on its ease for writing and reading mathematical expressions. In this sense, our proposal allows incorporating an easily readable and writable methodology to cope with math expressions when interactive spreadsheets are used and designed in Economics teaching. The resulting nearly plain text can be used with few or no modifications in other numerical computing programs.