Planning promotes studying – The higher the plan quality the better: A micro-randomized trial

• Self-regulated learning is crucial for vocabulary study outside the classroom. • Our mobile intervention aimed at helping children plan when and where to study. • Mobile prompts encouraged children to create if-then plans for studying the next day. • The effectiveness of the self-created plans crucially depended on their quality. • We highlight important criteria to consider when rating the quality of self-created if-then plans. Young learners often cram before exams instead of spacing out their study sessions. In this study, we investigated whether implementation intentions could help students develop beneficial study routines by planning when and where to study vocabulary. We conducted a 42-day micro-randomized trial to examine the effectiveness of a mobile intervention aimed at increasing children’s engagement with a vocabulary learning app. German-speaking fifth and sixth graders ( N = 357; 53.78 % female, M age = 11.63 years) received planning prompts on their smartphones on randomized evenings, asking them to formulate appropriate implementation intentions for the next day, that is, if-then plans specifying when and where they would like to study vocabulary. Using a micro-randomized trial allowed us to test the within-person effect of the intervention over time, as well as potential time-varying moderators. We used logistic mixed-effects models to examine whether receiving a planning prompt in the evening significantly increased the likelihood of studying with the vocabulary learning app the next day. Our results suggest that the effectiveness of the intervention was strongly dependent on the quality of the self-created plans. Using a categorical rubric to rate plan quality based on whether the cue of the plan was specific, salient, and appropriate in the given context, we show that the higher the plan quality, the more likely children were to study the next day. These findings suggest that if-then plans can be a useful metacognitive strategy for planning study sessions. Researchers and teachers should carefully scaffold the creation of high-quality plans by providing examples and feedback.