Chempy is a tool specifically designed to enter and check chemical formula using the standard notation of using subscripts for coefficients and superscripts for charges. Teachers configure Chempy by giving the formula (e.g., Na+ + Cl- -> NaCl) that students have to enter. Inside an ILS Chempy checks whether the student has entered the correct formula. Students can enter coefficients and charges using the _ and ^ keys which Chempy will display as sub- and superscripts respectively.