In order to read and understand texts, certain basic skills such as word recognition, decoding skills, vocabulary knowledge, and fluency are required. In PIAAC, these skills are assessed by means of 'reading components' – the building blocks of literacy. Tasks include recognizing simple words, or reading and understanding simple sentences.
Studies conducted by researchers in North America have shown that a significant percentage of adults have an extremely low level of literacy skills. The additional assessment of reading components in PIAAC makes it possible to determine the percentage in the population of the participating countries. Furthermore, some of the factors associated with very low literacy can be explored, providing valuable input for the development of possible intervention measures.