Pediatric resident education in child development has historically not been taught in a formal manner despite it being identified as a priority for residency education.1 A significant proportion of children with developmental delays are not identified until they enter school, representing a lost opportunity for early intervention and underscoring the importance of targeted resident education in child development.The advent and acceleration of technology enhanced learning (TEL) led to the development of innovative educational curricula flexibly accessed by a learner. Prior TEL endeavors teaching child development relied on strategies employing passive review of videos or online material. Spaced education is a framework centered on presentation of concepts delivered longitudinally and repeated at varied intervals, improving retention of knowledge. Prior studies demonstrate improved knowledge recall, with few that examined impact on clinical care or optimal integration into clinical rotations.2Daily Dose of Development (3D) is a web or mobile application with a comprehensive database of clinical vignettes mapped to updated developmental milestones. Vignettes are presented through cycles of multimedia questions, allowing spaced interactive application of knowledge in realistic scenarios. Curriculum development was informed by 2 feasibility studies assessing different delivery mechanisms, a targeted needs assessment of resident learners, and qualitative interviews with child developmental experts.A randomized control study was performed to evaluate the feasibility, acceptability, and preliminary effectiveness of the 3D app. All pediatric residents (n=90) at a single training institution were invited to participate in the study, 30 of whom were randomized to either the app or control group. Baseline demographic data were collected prior to launch of the app curriculum, which cycled over 3 months. Control group residents participated in existing curricular opportunities in child development without access to the app until study conclusion. Feasibility was assessed using surveys at the beginning, midpoint, and end of the study period, examining comfort level in child development, app usability and impact on clinical care, and open-ended questions. App usage data from Google Analytics were also collected.Out of 30 residents, 17 were randomized to the app and 13 to the control group. Fifty-seven percent (17 of 30) of residents completed all surveys: 8 (47%) in the app and 9 (53%) in the control group. Baseline demographics were comparable between groups.All 17 residents accessed the app during the study period. Of those responding to all surveys, 63% (5 of 8) accessed daily. The mean number of responses per quiz was 8.9 (ranging from 2-16 responses). Identified features to enhance the app included ability to download content, zoom in on multimedia, reference article links, customize push notifications, and stack missed questions.At study conclusion, 100% of the app arm endorsed 3D as effective for learning child development. Statistically significant improvement in comfort with milestone recall (P=.007), development evaluation methods (P=.001), and identification of developmental delay (P=.046) were noted between groups. Fifty percent (4 of 8) of the app group reported improvement in patient developmental assessments, compared to 33% (3 of 9) in controls (P=.49). Feedback demonstrated desire for ongoing education in child development, enthusiasm, and desire for incorporation of the app into existing traditional curricula. Loss to follow-up and small sample size limited analysis.This study demonstrated feasibility, acceptability, and preliminary effectiveness of app-based spaced curriculum as an adjunct to clinical rotations. Self-reported behavior change in clinical care as a result of participation in the app curriculum is a novel area of impact for this type of curriculum and requires further study. Future iterations focused on optimal implementation strategies are needed to develop best practices of integrating TEL curricula with traditional clinical teaching.