Recently, projected electronic slides have been the most common tool used in classrooms. However, electronic projection slides, such as PowerPoint slides, do not provide sufficient flexibility to augment the displayed materials; therefore, instructors are not able to adjust their instruction instantly in response to the audience reaction and needs. Accordingly, many studies have suggested the use of tablet PC-based presentation tools in order to enable real-time handwritten annotations on predeveloped materials. Based on this rationale, the present study was designed in order to examine the effects of a tablet device (iPad in this study)-based instructors' digital handwriting on students' learning. Participants were 36 undergraduate students: half of the students were instructed using the typical PowerPoint-based presentation without the digital handwriting of the instructor, whereas the other half of the students were instructed using a tablet-based presentation with the instructor's digital handwriting. Results from a MANCOVA revealed a significant main effect for the presentation mode. Two follow-up ANCOVAs revealed that students in the tablet-based instructor's digital handwriting condition significantly outperformed the students in the animated PowerPoint-based presentation lecture for conceptual knowledge acquisition, despite the fact that there was no statistical difference in factual knowledge acquisition.