Over a three-year period, chemistry and engineering students participating in six Research Experience for Undergraduates (REU) programs were surveyed before and after participating in a research ethics training workshop. The goal was to learn what undergraduate students already knew about key concepts in research ethics at the start of their research experience and to learn the impact of participation in the workshop on their knowledge and understanding of important research ethics concepts. At least two-thirds of the respondents could define fabrication of data, falsification of data, plagiarism, intellectual property, and confidentiality before participating in the training workshop. More than a third, however, could not define the terms personal misrepresentation, authorship, and conflict of interest. Though many students had factual knowledge of the key concepts at the outset, they were found to be unable to apply this knowledge to their summer research projects. Participation in the workshop was found to lead to improved comprehension of all the key science ethics terms selected for study in this project by all participants as reflected in the participants' ability to define the key concepts at the end of the workshop. Participation in the workshop, however, was not found to improve students' ability to apply their knowledge to their research projects. Student responses indicate that the students lacked critical local information on ethical standards needed for them to successfully apply their knowledge to their research projects. These findings together with those of our earlier work point to the importance of engaging individual faculty research mentors in their students' research ethics training.