The benefits of more electronic screen space on students’ retention of material in classroom lectures

Abstract

Many lecture halls today have two or more screens to be used by instructors for lectures with computer-supported visual aids. Typically, this additional screen real estate is not used to display additional information; rather a single stream of information is projected on all screens. We describe a controlled laboratory study that empirically assesses the effect on students learning of using the increased classroom screen real estate to project an additional stream of information. We measured how well participants learned from a two-stream presentation compared to a one-stream presentation duplicated on both screens. Data indicate that using extra screen real estate can indeed improve learning. In particular, learning was most improved when pertinent prior information was shown alongside currently explained information. There is also evidence that visual comparisons were improved with parallel viewing using extra screen real estate. Subjective data gathered from participants showed a strong preference for learning with two streams of content over a regular one-stream presentation.

Introduction

For many decades lectures were presented in classrooms with multiple blackboards, providing a large amount of “screen real estate” on which material could persist. With the advent of personal computers, commercial software such as PowerPoint, and digital projectors, many lectures now use computer-supported slides as their primary visual aids. Most studies that examined if computer-generated slides are beneficial in classroom lectures have found that students responded positively to the use of computer-generated slides when compared to blackboards or overhead transparencies (Bartsch and Cobern, 2003, Daniels, 1999, Savoy et al., 2009, Susskind, 2005, Susskind, 2008, Szabo and Hastings, 2000). Students indicated that slides help them improve organization of the course and their notes, help them learn course material more effectively, and make lectures more interesting and entertaining (Levasseur & Sawyer, 2006). How students react to computer slides is important, but an equally important question is whether computer slides actually influence student learning. Most studies examining the effect computer slides have on learning outcomes have found no significant improvement in student performance when slides were used, compared to using other visual aids such as overhead transparencies or blackboards (Bartsch and Cobern, 2003, Daniels, 1999, Savoy et al., 2009, Susskind, 2005, Susskind, 2008, Szabo and Hastings, 2000).

One reason that electronic slides might not be as effective as traditional visual aids is the lower screen resolution that PowerPoint lectures have compared to a blackboard lecture. Using PowerPoint, instructors typically use one medium-resolution projector screen to show their slides. This is not comparable to the resolution provided by a typical blackboard lecture (Lanir, Booth, & Findlater, 2008). A single medium-resolution screen limits the amount of information that can be presented, making it difficult to explain complex, non-linear concepts (Tufte, 2003). The restricted display area of slides may also cause authors to edit their content and eliminate details in order to fit onto slides, or to reorganize content onto two or more slides in a way that breaks the logical organization of the material being presented (Farkas, 2009).

As universities accommodate more students and face increasing financial and resource constraints, many classes, especially at the introductory level, are taught in large lecture halls. While most educators agree that smaller classes provide better learning environments with stronger student–instructor interaction, large lectures are likely to persist in the near future. Fortunately, the same economies of scale that have led to large class sizes and large lecture halls also allow universities to invest in technological infrastructure for lecture facilities (Wolfman, 2002). We thus find that many large lecture halls are now equipped with multiple projector screens. With increasing resolution on large displays, increasing computer power to support multiple displays and animation, and decreasing projector prices, it is likely that future lecture halls will have even more screen real estate using higher resolution projectors or more projectors. Lately, different software tools have been developed to make use of these larger electronic surfaces (Chiu et al., 2003, Lanir et al., 2008, Röüling et al., 2004).

We are interested in determining whether the more limited screen real estate usually available for computer-supported presentations compared to traditional blackboards has perhaps been detrimental to students’ learning. More positively, we want to know whether using additional screen real estate for computer-supported presentations might improve learning. Using more screen resolution to present more information and aid teaching is most evident when instructors use multiple sliding blackboards (we use the term “blackboard” to refer generically to either a traditional blackboard with chalk or to a whiteboard with felt markers). Multiple sliding blackboards in large lecture halls have been used for decades in many university courses. Lanir, Booth, et al. (2008) observed how instructors use a wide array of blackboards and compared that with the use of computer slides in classrooms. They found that many techniques easily used with blackboards have been made more difficult or lost with the move to computer-generated presentations. We summarize these findings: (1) A blackboard allows instructors to present ideas using a large surface that they can dynamically control: they can decide which information to erase and which to keep for future reference. (2) Multiple blackboards allow large amounts of information to be visible to students, which computer “slideware” systems seldom do. (3) Larger surfaces, such as multiple blackboards, are useful for supporting explanations of complex ideas. With more space, spatial relationship between concepts can be used to encode meaning. (4) Instructors use blackboards to show relationships between two concepts drawn on different boards, or to compare those items. (5) Because blackboards afford more screen space than computer slides, information can persist for a longer time. With blackboards, instructors would often refer back to previously written content during a lecture – sometimes to information recently presented, and other times to content originating much earlier in the presentation. With computers slides, this rarely happened.

In this paper we report a controlled study that considers the efficacy of using more screen space in electronic classroom presentations. To the best of our knowledge, no studies have thus far examined the advantages and tradeoffs of using extra electronic space. Our study was conducted in a classroom with two screens available for projection. We compared a “one-stream presentation” (i.e., a normal PowerPoint presentation with slides duplicated on each screen) with a “two-stream presentation” in which the additional screen real estate was used to present slide content that was different from the slides projected in the primary stream of information. The study evaluated whether students learned better when presented with information in two-streams on the two projected surfaces compared to a regular, one-stream presentation duplicated on both surfaces. In particular, we examined different practices for presenting the additional information in the second stream to see if they have an effect on students’ learning.