This work develops and experimentally evaluates the prototype of a digital narrative interface that pretends to, simultaneously, exercise the reading comprehension and the resolution of elementary verbal arithmetic problems (EVAP). The prototype consists of an interactive story which includes various types of EVAP and incorporates a graphing calculator based on the «yupana» craft or «Incas abacus». The results of a qualitative validation carried out individually with 18 children of second grade of primary education suggest that the way to locate and present the numerical data of each EVAP is determinant to facilitate its correct resolution. The conclusions specify the qualities of an interdisciplinary narrative interface model and argue that, in order to achieve the expected learning, it is necessary to promote a sequential, metered, rewarding and visually attractive reading. In addition, it discusses the possible impact of touch screens in audiovisual language and the design of school textbooks.