Back to School with Tablets Embedded in Digital Desks

A digital-desk pilot program in Brazil uses a unique display design to provide an interactive interface developed to enhance education and minimize ergonomic concerns.

by Victor Pellegrini Mammana, Cynthia Yukiko Hiraga, Ana Maria Pellegrini, Daniel den Engelsen, Luiz Alberto Castro de Almeida, Alexandre Cândido de Paulo, Gustavo Junior Alves, Miguel Joao Neto, Carlos Ignacio Zamitti Mammana, and Antonio Carlos Camargo do Amaral


PROVIDING high-quality education is important everywhere, but in Brazil, in parti-cular, education has become a top priority because of its importance in the fight against social and economic inequality. For this reason, the Brazilian Federal Government has been encouraging R&D with regard to information technology for education and digital inclusion. One of the approaches currently being pursued is the intensive use of computers inside class-rooms. While computer labs and laptops – the latter especially as provided by the One Laptop Per Child program – go far toward providing anenriching technology experience in the class-room, digital desktops are an additional and intriguing educational option.

One of the foremost researchers in the field of education and technology is Seymour Papert from MIT, who has explored opportunities related to the use of computers with a focus on math teaching.1 He later extended this exploration to other disciplines. In 2005, the MIT program "One Laptop Per Child" (OLPC) proposed by Nicholas Negroponte was presented to the Brazilian Government as a way of transferring the ideas of Dr. Papert and other educational gurus from the academic scene to reality. The proposal by Negroponte2 was based on the idea that all school children should experience so-called "one-to-one technology," i.e., each child would have his own laptop, provided by the federal government. In practical terms, approximately 45 million laptops would be required to supply the Brazilian public schools. Although the ideas included in Negroponte's proposal have evolved from 2005 to the present, the main concepts of the OLPC program – free distribution of laptops to kids and teenagers with full access to the Internet – still remain vivid in the heads of policy makers all over the world.

Many programs based on the intensive use of computers in the classroom have shown excellent results – in the appropriate environment. However, when the environment includes individuals with a variety of educational, social, economical, and political backgrounds, results are more mixed. We will not go further into this here; however, the main focus of this article is to discuss some of the aspects of different types of computer systems inside classrooms. The issues presented here are in part based on the results of a study of the OLPC program that was conducted by the authors on behalf of the Brazilian government.

Computer Labs

The most common approach to introducing computers into schools in Brazil is with a separate room called the "computer lab" that contains about a dozen systems. Such a room is shared among all students of a given school. In many cases, a group of students shares a mouse and keyboard and each student may actually use the computer for only a few minutes. On several occasions, we heard educational experts state that computer labs remain locked most of the time. Although we did not quantitatively examine such statements, it appears that the locked computer lab is not a myth. Through visits and interviews with administrative staff and teachers in Brazilian primary schools, we collected statements such as "children break computers" and "I don't want trouble if the computer lab breaks." If intensively used, the "computer lab" poses a further concern: the existence of a display between the student and other individuals inside the classroom (including the teacher) can provide an undesirable element of segregation.


The one-to-one computer strategy as proposed by Negroponte is a way of circumventing the tragedy of the locked computer lab because it gives children full access to computers anytime. This strategy obviously has the potential for mobility if sufficient battery time is provided; otherwise, dependence on multiple outlets in the classroom is unavoidable. The OLPC program has focused on a solution that minimizes power consumption, which also limits the display's maximum size and processor performance because the LCD backlights are responsible for a significant part of the power consumption in laptops. The bill-of-material of a laptop indicates another limitation to display size: it is one of the most expensive parts of the computer. For a project such as OLPC, weight, cost, and power expenditure needed to be minimized, leading to laptops that originally had display sizes of about 7 in.2

Finding a sufficient number of outlets to power the laptops, and using the outlets without creating a tangle of confusion during the school day, can be a challenge in the typical Brazilian public school. In more organized pilots, such as the one sponsored by Bradesco Schools in the city of Campinas, the laptop batteries are charged during break time, thus providing a mobile experience for two periods of 2 hours each day.

Another potential drawback for laptops is that of ergonomics. Recently, we have studied the use of laptops by children and we agree, in general, with Hedge's statement3 that "laptops are intrinsically non-ergonomic because the display and the keyboard are integrated into a single piece." In other words, when the display is adjusted to fit the position of the user's eyes, the keyboard is in an unnatural position. When the keyboard is adjusted to fit the user's hands, the display is in an unnatural position. However, all statements related to ergonomics are subject to investigation and debate. For instance, it is reasonable to accept that many activities of children are non-ergonomic, such as "watching TV in a wrong posture, intensive sporting, intensive music practicing, video gaming, and even hand writing".4 This is not, of course, to dismiss consideration of ergonomics as a mere trifle.

In the evaluation of the OLPC program, we also analyzed the cognitive consequences of small displays by comparing quantitatively the user performance among displays of 15, 10, 8, and 7 in. In this study, tasks demanding interaction with displays were performed by two groups: 18 children from 6 to 12 years old and 20 adults from 19 to 29 years old. The time required to perform the same task in each display size was used as an indication of the user's effort to achieve the interaction goals. We believe longer times needed to perform the same tasks indicated higher levels of difficulty that resulted from a less-comfortable interface. For the adult group, there was a consistent trend of longer times for smaller displays; for the children's group this trend was not statistically significant. We attribute this difference to the fact that the group of children in the test had very little experience with computers in general and mice, in particular, leading to longer times to perform the tasks regardless of display size. We believe that if the two groups had possessed similar computer experience they would have both performed more quickly on the systems with larger displays.

Conventional Input Devices

The discussion of whether intensive keyboard and mouse use can cause occupational hazard, pain, or other physical complaint is an ever-green in the literature. Keir et al.5 reported that "the carpal-tunnel pressures measured during mouse use were greater than pressures known to alter nerve function" in 14 healthy individuals evaluated in their work. However, a study conducted by Andersenet al.6 involving thousands of individuals indicated an unlikely connection between keyboard use and risk for developing carpal-tunnel syndrome. Again, controversy is present. Our decision to use a tablet in a digital desk instead of a conventional input device stemmed from a different motivation: we believe that with a keyboard, touch pad, or mouse the information surface (display) is separated from the points of motor interaction, leading to a less attractive and intuitive experience than the one offered by touch screens and transparent tablets.


We define a tablet as a device constituted by a flat surface that is capable of identifying the position of one or more styli that touch its surface or "hover" over it. We have developed a new type of low-cost tablet that is based on a resistive principle (one of our authors has a U.S. patent for it). As opposed to conventional resistive touch screens, ours does not require two layers separated by spacers. We do not use ITO conductive layers, but SnO2 instead, which costs much less and can be deposited at atmospheric pressure. High transparencies can be obtained in the 90% range in our tablet, while robustness is guaranteed by the outstanding tribological characteristics of SnO2 on glass.

Figure 1 shows the working principle of a resistive tablet, in which the position is determined by measuring the voltage drop using a conductive stylus along a uniform resistive and transparent film. It is assumed that the voltage is approximately linear with the position (actually linearization algorithms are required to make the tablet work appropriately). In our tablet, we manage to obtain "X" and "Y" by switching the current in perpendicular directions in the SnO2 film, and that is why only one layer is required. The current design allows control of the cursor when the stylus is not in contact with the surface.



Fig. 1: The tablet has a general working principle similar to many other resistive solutions: the measured voltage is linear with position. Instead of having conductive layers in parallel, we use a single film for X and Y by changing the direction of the current from cycle to cycle. This solution reduces cost substantially.


Digital Desks

During the last two SID-sponsored LatinDisplay conferences in Campinas (November 2007 and 2008), the small Brazilian city of Serrana participated in exhibitions showing a new technology that provided one-to-one experiences within classrooms; i.e., each student using a computer integrated into a school desk (Fig. 2).

The technology is basically a low-cost metallic school desk with a display integrated into the table top, which consists of a robust and transparent plate, such as thick glass. This plate has a stylus-based tablet technology, or alternatively a touch-screen technology, applied to it, allowing the direct interaction with the desk display image. The table top can be used in the horizontal position, as indicated in Fig. 2, or vertically, or in any intermediate position. Two models are now available: a PC board integrated into the tablet top and a multi-terminal version, in which five desks are connected to a single computer, allowing independent operation by each user.

We believe that this Digital School Desk is a way to overcome the challenges of conventional computer labs and laptops as mentioned earlier in this article. First, if the Digital School Desk is made available in the regular classroom, there is no need to lock it in a computer lab. Next, the table top of the Digital School Desk can be positioned horizontally, enabling an open line of sight between students and teachers, and it has a transparent tablet or touch-screen integrated on the table top, allowing direct interaction with the display image. The Digital School Desk can also substantially increase the number of hours spent by children with computers that offer less health risk (although an educational program based on digital desks will also require measures to guarantee their rational use in order to further reduce risks). This type of desk has more options to circumvent health hazards through ergonomic optimization than laptops. Because there is no limitation on power, large displays can be used, offering better options of visual interaction for students. Last, making the desk furniture adjustable is easier than making laptops adjustable, so multiple-sized devices can be avoided.

On the downside, the Digital School Desk cannot offer the mobility of laptops, which implies that it can only be used in the classroom. Digital School Desks are also designed to be connected to power outlets on a permanent basis, which will require the rewiring of the classroom. (This, however, is also the case for intensive laptop usage at school, since battery life constantly reduces as the recharging cycles increase). Making laptops really mobile in Brazilian schools may require frequent battery substitution, a challenge for which our cities are not prepared with regard to supply and environmentally responsible disposal.



Fig. 2: One of the first versions of the "Digital Desk" was demonstrated at Latin Display 2007. The child is using the stylus to interact with the display image.



Fig. 3: This Serrana public classroom is fully equipped with Digital Desks, air-conditioning, and a digital board at the front of the room. Students in this picture are using the multi-terminal version: one computer is a server for five desks. The digital board at the front of the classroom is based on a projector (courtesy of the city of Serrana). The table tops can also be put in horizontal position during operation, to ensure a clear line of sight between teacher and student.


Figure 3 shows the first classroom fully equipped with the multi-terminal version of the desks. The full concept in the city of Serrana includes a digital white board and air- conditioning, which is rarely present in Brazilian public schools. The use of air-conditioning itself may be a key factor in improving education because it can provide thermal comfort for kids in very hot areas, although we do not have quantitative data on which to base this statement yet.

It is too early to evaluate the impact of the desks on the learning performance of the students at Serrana, but according to the comments of the teachers involved with the pilot study there, the new technology certainly has already changed their attitude toward the school environment, increasing attendance and motivation. We believe that digital desks can serve as key components not only toward a more satisfying technology interface, but toward a better educational outcome overall.


The development and evaluation of the Brazilian Digital School Desk is the work of many individuals. We would like to thank all of them for their contributions. Daniel den Engelsen acknowledges the financial support from FAPESP. We would like to acknowledge the support from SECIS/MCT and thank Prof. Afira Ripper from UNICAMP for his helpful discussions.


1S. Papert, Mindstorms: Children, Computers, and Powerful Ideas (Basic Books, New York, 1993).

2N. Negroponte, Brazil Plan – One Laptop Per Child (OLPC) (The Media Lab, Massachussetts Institute of Technology and OLPC non-profit Association, 2005).

3A. Hedge, "Tips for using a laptop computer," retrieved Nov. 2008 from http://

4G. Panagiotopoulous, K. Christoulas, A. Papanckolaou, and K. Mandroukas, "Classroom furniture dimensions and anthropometric measures in primary schools," Applied Ergonomics 35, 121-128 (2004).

5P. J. Keir, J. M. Bach, and D. Rempel, "Effects of computer mouse design and task on carpal tunnel pressure," Ergonomics 42(10), 1350-1360 (1999).

6J. H. Andersen, J. F. Thomsen, E. Overgaard, C. F. Lassen, L. P. A. Brandt, I. Vilstrup, A. I.Kryger, and S. Mikkelsen, "Computer Use and Carpal Tunnel Syndrome," Journal of the American Medical Association 289, No. 22, 2963-2969 (2003). •


Victor Pellegrini Mammana, Daniel den Engelsen, Luiz Alberto Castro de Almeida, Alexandre Cândido de Paulo, andAntonio Carlos Camargo do Amaral are with the Renato Archer Information Technology Center (CTI). Cynthia Yukiko Hiraga is with the Escola de Artes, Ciências e Humanidades, Universidade de São Paulo (USP). Ana Maria Pellegrini is with the Instituto de Biociências, Universidade Estadual Paulista (UNESP). Gustavo Junior Alves, Miguel João Neto, and Carlos Ignacio Zamitti Mammana are with Associação Brasileira de Informática (ABINFO).