The training of effective teachers has been one of the main aims of educational systems, in so far as it could be an important tool to improve the education performance of children and, consequently, contribute to their career progression and foster social mobility towards a more meritocratic society. The present study intends to identify these teachers by their ability to engage young students in lessons, which may reflect the capacity of their teaching practices and efficient use of available resources to increase students' learning. We focus on 4th-grade reading and mathematics teachers in Spain--using TIMSS and PIRLS 2011 data--and we propose a 2-step procedure for this analysis: the 1st step obtains teachers' efficiency scores, which are later employed in a 2nd step--together with teachers' practices--to explain children's engagement in lessons.