Martine van der Pluijm

135 How to support lower-educated parents? Instruments and measures We developed a questionnaire for parents for individual interviews. We used translators to accommodate parents with low Dutch language proficiency. The questionnaires consisted of the following: Demographics : education levels (1= no education, 2=a language course, 3= primary school, 4=secondary education 12-15 years, 5=secondary education 16-18 years, 6=senior secondary vocational education, 7=university), migration background (defined by the country of birth of mother), home language (the language used at home with their child) and gender. Parent use of parent-child activities : (0= never, 1=sometimes, 2=often). Parent perceptions of the SFP (open questions). We asked parents the following four questions: • What did you like about the relationship with the teacher? • How can you further improve your relationship with the teacher? • What did you like about how the teacher helped you to support your child in developing oral language? • How can collaboration with the teacher be improved? Parent perceptions of the SFP (scales). We used the Parent Involvement Project scales (Hoover- Dempsey et al., 2005) and derived three constructs on a six-point Likert scale, ranging from 1 (disagree strongly) to 6 (agree strongly). 1) Parent perceptions of the SFP in general . We used the items of two of the original PIP scales: Parent perception of invitations to be involved in school (e.g., “I feel welcome at this school”) and Parent perception of their knowledge and skills to communicate with school (“I know how to communicate effectively with my child’s teacher”). Cronbach’s alphas for the construct (19 items) are α=.84 at pretest and α=.84 at posttest. 2) Parent perceptions of a SFP to stimulate children’s oral language development . We adjusted the above scales of the Parent Involvement Project (Hoover-Dempsey et al., 2005) and created a new scale: Parent perception of invitations to be involved in oral language support (e.g., “My child’s teacher gives me suggestions to support my child’s oral language development.” Cronbach’s alphas for the construct (four items) are α=.68 at pretest and α= .73 at posttest. 3) Parent perceptions of their self-efficacy to promote language development at home. We adjusted two scales of Hoover-Dempsey et al. (2005). These are: Parent perceptions of their knowledge and skills to support language development at home (e.g., “I know how to