Students’ interest in science declines in secondary school. Therefore, motivating students to become competent and engaged in science topics that are relevant for their everyday lives is an important goal, so they can be better citizens and decision makers with socioscientific issues (e.g., climate change and waste disposal). The present study contributes to research on activity emotions (state) and motivational outcomes (situational interest and situational competence) in science education. The study compared three experimental groups in a guided inquiry lab work on the chemistry of starch and a control group. The three groups were (i) 13 science classes taught at school; (ii) 14 classes taught in a Science Center Outreach Lab (SCOL) visit; and (iii) 17 classes taught in a combined setting of (i) and (ii); the groups were taught on the same topic. The large sample of classes was randomly assigned to the experimental conditions and a control group and data were analyzed for the theoretical part and the practical part of the intervention. The nested data were analyzed using item response theory and multilevel analyses. The three lab‐work conditions were quite successful in comparison with the control group. There were some differences between the SCOL and school groups; the students experienced higher enjoyment in the theoretical part of the intervention in the school group and higher situational competence in the practical lab work at the combined setting. Especially low achievers profited from the intervention, supposedly because the topic was close to students’ everyday lives. Conscientiousness was a major predictor of emotional and motivational outcomes. In conclusion, experimental lab work at a SCOL can be seen as a supplement to a worthwhile STEM education. © 2016 Wiley Periodicals, Inc. J Res Sci Teach 54: 3–28, 2017