In an ongoing effort to improve the quality of medical education and reach goals for excellence, it is important to create a stimulating learning environment for both students and teachers [
1]. A relevant instrument to challenge students and teachers is assessment, as it not only drives learning but it may also help learning, the so-called ‘testing effect’ [
2]. Recent work by Karpicke and Roediger has demonstrated that increased learning by testing takes place by retrieval practice, not by repeated learning [
3,
4]. Underlying mechanisms include (a) focusing students on the relevant topics, (b) increasing students’ motivation, and (c) training students’ capacity to answer questions [
5]. Increased learning by testing has not only been demonstrated in a laboratory environment [
3,
4], but also in a more realistic setting, i.e. an ongoing course in a regular academic curriculum [
6,
7]. In a previous study using a prospective controlled design, we demonstrated that an interim assessment during an ongoing bachelor course for (bio) medical students resulted in a higher score in the course examination [
7]. As this study was performed during a small group work (SGW) session without explicit feedback from the interim assessment, and feedback is supposed to enhance learning by testing [
3,
5,
8], we decided to embark on a follow-up study including feedback as an intervention. Since there are some indications that females are more susceptible to feedback [
9], we felt it worthwhile to also study the effect of gender.
Based on a literature review, feedback can be defined as ‘Specific information about the comparison between a trainee’s observed performance as a standard, given with the intent to improve the trainee’s performance’ [
10]. The purpose of feedback is to reduce discrepancies between the current understanding or performance and the desired goal [
11]. It is believed that feedback provides the route by which assessment becomes a tool for teaching and learning, and it is central to the concept of formative assessment [
12,
13]. Although the power of feedback is extensively emphasized in the literature, there are only a few studies that have systematically investigated the power of feedback within the classroom [
13,
14]. According to a systematic review performed by Veloski et al. feedback is most effective when provided by an authoritative, credible source. These authors recommend that the effects of feedback should be studied separately from those of other concurrent interventions, such as implementation of practice guidelines or educational programmes [
15]. This implies that studies on the effects of feedback in (medical) education should adhere to a well-defined description of the feedback given, and be executed with an unequivocal experimental design.
Based on these considerations we wanted to determine whether: (1) explicit feedback following an interim assessment during SGW has an effect on the formal examination score, and (2) the effect of feedback is influenced by gender. This was done by means of a prospective randomized study using a cross-over design.