A Randomized Controlled Trial of a Large Scale Systematic and Explicit Language and Literacy Intervention in Danish Daycares: The SPELL Study

Background: Children’s early language and literacy skills are key predictors of later educational outcomes. Children from low socioeconomic status and immigrant backgrounds have elevated risk for adverse educational outcomes. Research suggests that systematic and explicit curriculum-based language and literacy interventions may have positive impacts on children’s outcomes. However, the majority of this research has consisted of efficacy trials conducted in the U.S. on a relatively small number of children from low-income homes and focussed on efficacy instead of effectiveness. As a large-scale effectiveness trial, the Structured Preschool Efforts for Language and Literacy (SPELL) study will test the generality of the value of systematic and explicit instruction by evaluating the effects of an intervention in Denmark conducted under “real-life” circumstances including all children in the participating daycares addressing questions both relating to the efficacy and effectiveness of the intervention.
Methods: The SPELL study is a cluster-randomized trial of a language and literacy intervention which uses storybook reading with systematic and explicit instruction to promote language and literacy skills in Danish children. Based on sample size calculations, we intend to include 128 daycare centers, each with on average three classrooms and 20 children/two daycare educators in each classroom, summing to 7.680 children and 768 educators. Daycare educators will implement a 20-week intervention which provides an explicit scope and sequence of language and literacy instruction over 40 lessons. The potential added value of coupling SPELL with an expanded professional development program and with a supplemental program implemented by parents will be tested. The primary outcome is the change of language scores from pre to post intervention in all participating children. A range of secondary outcomes and moderator analyses will be conducted.
Discussion: It is uncertain how findings from studies of systematic and explicit interventions in the US will translate into non-US societies, and how effective such interventions are at a large scale. This study will be the first large scale study to address both questions. The findings will indicate the generality of the effects of systematic and explicit instruction in a non-US context and identify implementation factors that affect the efficacy of language and literacy interventions when carried out at scale.