Word problems represent a significant part of the mathematical learning content in primary grades. The main activities that students perform related to word problems are solving and composing word problems. Both processes require the application of specific cognitive processes, which are often supported by different types of visuality. Diagrammatic representation is an extremely appropriate tool to support the encoding and decoding processes associated with the multitude of data in the content of word problems. Diagrams significantly support the effectiveness of working with word problems in the teaching of mathematics in the primary grades.