Problem-based learning or PBL in short, is an instructional approach that helps students develop flexible understanding and lifelong learning skills (Hmelo-Silver, 2004; Schmidt, Loyens, Van Gog, & Paas, 2007; Simons & Klein, 2007). In general, the main instructional material used in the PBL curriculum is the problem, which is designed to trigger learning at the start of the lesson. In the course of the PBL tutorial process, students are trained to collect information, analyse data, develop hypothesis, and apply strong deductive reasoning to the problem at hand (Barrows & Tamblyn, 1980; Hmelo-Silver, 1998; Schmidt, van der Molen, te Winkel & Wijnen, 2009). Throughout this process, learning supports (i.e. scaffolds) may be provided to students as form of guidance and assistance to their understanding of the problem or task assigned. Besides the problems, advocates of PBL do not forbid structured educational activities and guidance where appropriate (Brush & Saye, 2002; Ertmer & Simons, 2006; Simons & Klein, 2007; Taylor & Miflin, 2008). These additional sources of support include references, audiovisual aids and even lectures relevant to the problem. The main focus of this thesis is about how scaffolds can be used to impact student learning in problem-based learning (PBL) environments.