Robin van Rijthoven

17 General introduction 1 analysis of Galuschka and colleagues (2014) it was mentioned that some studies did incorporate some writing activities, whereas other studies did not include writing activities at all. As mentioned earlier, reading and spelling are reversed processes and combining reading and spelling during instruction and practice can be beneficial for both learning to read and learning to spell (e.g., Conrad, 2008) as better orthographic representations (e.g., spelling) could facilitate phonological growth. Thus, according to Galuschka and colleagues (2014) most interventions focus on the orthography to phonology relationship instead of the bi-directional relationship that is stimulated when reading and spelling are combined. A phonics intervention that incorporates spelling is a so-called phonics through spelling intervention (as described in Ehri et al., 2001) in which the recoding process of spelling is learned in addition to the decoding process. The few studies regarding phonics through spelling intervention (i.e., phonics interventions with the inclusion of writing activities) found effects for word decoding (e.g., Tijms, 2011), pseudoword decoding (e.g., Kirk & Gillon, 2009), and spelling (e.g., Kirk & Gillon, 2009). These findings highlight the importance of a high-quality bi-directional relationship between both phonological and orthographic representations in learning to read and spell and show the benefits of a phonics through spelling intervention. As spelling is more difficult to learn than reading (Bosman & Van Orden, 1997; Ehri, 1997; O’Connor & Jenkins, 1995) one would expect that phonics through spelling interventions would include both reading and spelling instructions and divide time at least evenly. However, in the aforementioned studies very limited amounts of time were spent on spelling activities (at most onethird in Tilanus et al., 2016). Therefore, more research is needed to determine whether a phonics through spelling intervention with more time for spelling can be effective in increasing both reading and spelling levels of children with dyslexia. When including spelling it is important to start with a strong base of phonological processes in spelling based on grapheme-phoneme translation and add specific and complex orthographic processes in spelling by learning children morphological and orthographic patterns later on (Caravolas et al., 2001). For spelling, it was found that phonics, morphological, and orthographic interventions are all effective in treating spelling problems of children with dyslexia (Galuschka et al., 2020). One way of addressing phonological and orthographic errors separately is to analyze and categorize spelling errors. Spelling errors can be subdivided into three broad categories in order to define the source of the errors: phonological, morphological, and orthographic errors (Tops et al., 2014; Vanderswalmen et al., 2010). Previous studies showed that children with dyslexia (before an intervention) do not make qualitatively different, but more phonological, morphological, and orthographic spelling errors compared to typically developing children (Bourassa & Treiman, 2003; Bourassa et al., 2006). However, studies