Teaching others helps science graduate students to improve their own research skills, according to a study (D. F. Feldon et al. Science 333, 1037–1039; 2011). The work compared science, technology, engineering or maths (STEM) graduate students who teach with those who only conduct research. It examined the quality and testability of hypotheses by the students at the start and end of an academic year, as well as the strength and design of their experiments, on the basis of assessments by independent scientific reviewers. The analysis is the first of its kind to measure the growth of skills, says lead author David Feldon, who studies STEM education at the University of Virginia in Charlottesville. He theorizes that teaching in STEM enhances early-career scientists' understanding of what comprises good research.