Observing individual children in early childhood classrooms using Optimizing Learning Opportunities for Students (OLOS): A feasibility study

•OLOS is a new technology-based observation system that captures the learning experiences of individual children in classrooms.•By observing individual children in classrooms, we can elucidate classroom learning environments that are optimal for them.•OLOS was feasible in pre-kindergarten classrooms.•Children who shared the same classroom experienced different learning opportunities with most time spent in language and literacy activities.•The more teachers talked in ways capture by OLOS, the more the children in their classrooms talked.