The importance of advancing the 'employability skills' of students throughout their undergraduate education has been increasingly recognised by students and university instructors. Development of these essential skills is hindered by the lack of widely available assessment tools and shortage of detailed descriptions of effective instructional strategies. Evidence supports use of active learning in small groups for advancement of several transferable soft skills, including teamwork, critical-thinking and problem-solving skills (PSS). In this study, a previously reported testing strategy was used to measure the progress of generic PSS of students taking a one-semester, final-year undergraduate biochemistry course. Mixed-mode delivery based on a 'flipped classroom' approach allowed introduction of significant active learning components, including problem-based learning (PBL) in small teams (seven-eight students), workshops, bonus testing and lectures. Detailed descriptions of the instructional techniques used together with the COVID-19 pandemic-forced transition to fully online tutor-less PBL are provided. Data collected over two consecutive years demonstrate statistically significant improvement in the PSS test scores for the 89 students taking this course. Marks of students obtained in three different assessments (examinations, peer evaluations and PSS tests) are compared, revealing medium to low correlation. The benefits resulting from introducing active learning techniques and multiple assessments in undergraduate classes are discussed.