of learning objects. There are both proprietary and open, non-commercial and commercial, peer-reviewed repositories of learning objects such as the Merlot repository. Sharable Content Object Reference Model (SCORM) is a collection of standards and specifications that applies to certain web-based e-learning. Other specifications, such as Schools Interoperability Framework, allow for the transporting of learning objects, or for categorizing metadata (LOM). Artificial intelligence As artificial intelligence (AI) becomes more prominent in this age of big data, it has also been widely adopted in K-12 classrooms. One prominent class of AI-enhanced educational technology is intelligent tutoring systems (ITSs), designed to provide immediate and personalized feedback to students. The incentive to develop ITS comes from educational studies showing that individual tutoring is much more effective than group teaching, in addition to the need for promoting learning on a larger scale. Over the years, a combination of cognitive science theories and data-driven techniques have greatly enhanced the capabilities of ITS, allowing it to model a wide range of students' characteristics, such as knowledge, affect, off-task behavior and wheel spinning. There is ample evidence that ITSs are highly effective in helping students learn. ITSs can be used to keep students in the zone of proximal development (ZPD): the space wherein students may learn with guidance. Such systems can guide students through tasks slightly above their ability level. Recent works have also focused on developing AI-enhanced learning tools that support human teachers in coordinating classroom activities. The teacher can support students in a way that AI cannot, but is unable to process the large amount of real-time data analytics provided by the computer system. On the other hand, AI can share the workload and recommend the best course of action (e.g., by pointing out which students require the most help), but can only operate in the pre-specified domain and cannot handle tasks such as providing emotional support or remedial lessons to students in need. However, existing systems were designed under the assumption that students progress at the same pace. Understanding how to support teachers in a realistic, highly differentiated, self-paced classroom, remains an open research problem. Settings and sectors Preschool Various forms of electronic media can be a feature of preschool life. Although parents report a positive experience, the impact of such use has not been systematically assessed. The age when a given child might start using a particular technology such as a cellphone or computer