طراحی ارگونومیک ایستگاه کار کامپیوتر / مبلمان کلاس درس برای دانش آموزان کلاس اول در مدرسه ابتدایی

Children have been known to spend over 30% of their time at school. Most classroom activities involve sitting for long periods of time, with little or no breaks. Every effort should be made to ensure that young children do not experience back pain and other musculoskeletal disorders due to prolonged sitting on improperly designed classroom furniture. This paper proposes a methodology and guidelines for the design of ergonomic-oriented classroom furniture for first graders in the elementary school. The anthropometric measures of twenty first graders were used to develop regression equations for the furniture dimensions. The analysis of the relevant anthropometric measures such as stature, weight, body mass index (BMI), popliteal height, buttock-popliteal length, and hip breadth shows that stature and body mass index are important factors in the design of the classroom furniture. Adjustability was incorporated into the design in order to recommend the appropriate dimensions for the design of the classroom furniture. Based on the need to accommodate at least 90% of the population of first graders in the United States, this paper proposes furniture design dimensions for seat height (25.83–32.23 cm); seat depth (27.41–33.86 cm); seat width (17.91–23.29 cm); back rest (35.64–44.37 cm); arm rest (16.28–20.68 cm); and desk height (30.12–37.85 cm). This anthropometric analysis could be used to design ergonomic-oriented classroom furniture which would not only incorporate adjustability, but also improve the level of comfort for the intended users.

The use of furniture has been traced back to the Stone Age, during this period, the handy man carved out chairs and tables from stones and rocks. In the ancient civilization, the chair was one of the first types of furniture which was created in order to convey status, kingship and authority. Recent archeologists have discovered images of early furniture of ancient civilizations, especially in Ancient Egypt. The chair and table changed very little for several thousand years. The chair was typically pictured with a low seat and slightly reclining back as seen in the thrones and folding stools of the Egyptian Pharaohs (Schwartz et al., 1968). Furniture designs continued to change over time, and by the mid 19th century, the influence of Industrial Revolution and mass production further enabled chairs and tables to be manufactured in large quantities, various sizes and forms (Fiell and Fiell, 1993). Anthropometry and ergonomics have been used to develop new furniture forms which include task, or office desks and chairs by incorporating adjustability in order to accommodate a wider range of people and population. This is not only aimed at suiting a range of users, but also a range of postures (Lueder and Rice, 2007). Although adjustability has been a primary criterion in many designs, by the early 1960s, the value of adjustable furniture became an issue for debate in cases where there are more than two dimensions to adjust and users have difficulty in determining what fits best, which is often worsened by fatigue. By the early 1990s several manufacturers commenced the mass production of the modern furniture, especially chairs in different sizes and dimensions, based on reliance on the anthropometric data available to the designers (Cranz, 1998). Actual chair and desk dimensions are determined by measurements of the human body or anthropometric measurements. Anthropometric statistics may be gathered for mass produced furniture and designs are made based on these statistics. Until recently, the design of school furniture for children has received little or no interest. The focus of ergonomic design of furniture has been traditionally based on the design of work furniture based on the anthropometry and biomechanics of the human body. Numerous researches investigated prolonged sitting in the work place and proposed design principles for chairs and desks, especially for the computer workstation (Cook and Kothiyal, 1998 and Kumar, 1994; Villanueva et al., 1996; Burgess-Limerick et al., 1999). Although several ergonomic-oriented designs have been proposed for classroom furniture, this research intends to effectively recommend design guidelines for elementary school furniture by conducting an initial evaluation of the current furniture design in a particular school. Further analysis is then carried out to obtain the relevant design parameters and dimensions for the ergonomic-oriented classroom furniture based on the need to adequately accommodate at least 90% of the entire population of first graders in the United States. 1.1. Research motivation Several elementary schools in United States and around the world, especially in developing countries are often faced with ergonomics-oriented problem of inability to match students with the available classroom furniture, desks or computer work stations (Panagiotopoulou et al., 2004 and Gouvali and Boudolosa, 2006). Economical problems, budget constraints and lack of educational funding in several countries have also led to the problem of inadequate class room furniture in the elementary schools. Overcrowding and increase in student population is also one of the major problems facing numerous elementary schools (Rumberger, 2002 and Ready et al., 2004). It should also be noted that anthropometric dimensions of children such as stature, weight, and body mass index (BMI) have increased over the years. This is due to changes in their standard of living, eating habits and lack of adequate exercise (Figueroa-Colon et al., 1997, Jung, 2005 and Jackson-Leach and Lobstein, 2006). In the quest of designing effective ergonomic-centered classroom furniture for elementary school children, it will be very important to examine the design of the existing furniture in the school by performing general inspections. In this research, a local elementary school was selected and the existing furniture was examined based on the functional efficiency, ease of use, comfort, as well as health and safety (Pheasant, 1998). Examination of the current furniture in the elementary school revealed several design inadequacies such as the lack of cushion on the hardwood benches, and ergonomic concerns such as elongated benches and desks which do not have back rests. Other observed problems include overpopulation, where at least 6 children seated on a bench which was initially designed to seat only 3 or 4 children. In addition to this, several children complained of body aches and pains, which could be an indication of the ergonomic problems and design flaws identified during the inspection of the classroom furniture. In order to provide a tangible justification for this study, 126 first graders, 66 boys and 60 girls (average age of 6.5 years) were randomly selected from three additional elementary schools and each student was given a questionnaire to complete. In order to protect the confidentiality of the investigation, the names of the children were not required on the questionnaire. The result obtained from the survey is similar to the survey conducted by Parcells et al. (1999). The survey revealed that the majority of the children (95%) attended classes more than three times a week and were seated in the classroom for more than four hours daily (93%). This shows that children spend a huge part of their school hours in the classroom. Storr-Paulsen and Aagaard-Hansen (1994) observed that 8 and 9 year old children often tend to sit for more than an hour within any given hour and half. According to Dillon (1976), nursery school children are seated for almost 40% of their time in the classroom. Sitting still for a long period of time can cause the blood to move more slowly. Blood pools in the larger veins of the legs, and clots may form leading to a medical condition known as deep venous thrombosis (DVT). A large number of the students also claimed that their classroom furniture was not comfortable. Additionally, approximately 58% of the children claimed to have been absent from school at least once in the last 4 weeks, primarily due to aches and pains. The rating of the severity of the aches and pains and how often the aches and pains occurred revealed that over 50% of the children experienced pains and aches in each of the following major areas of their body: neck area, low back, hips, buttocks, thighs, wrists, knees, hands, and the ankles. The degree of pain ranges from slight to unbearable, and often occur either everyday or sporadically. The result of this survey provided sufficient justification for further research based on the need to provide effective recommendations for the design of ergonomic-oriented classroom furniture for the first graders since school children have been found to often spend over 30% of their time at school (Linton et al., 1994).

The results of the analysis indicate that appropriate ergonomics-oriented classroom furniture could be designed based on the data obtained from the intended users. In most cases, improper desk – chair combination are often the major reasons why children experience some level of discomfort while in the classroom. Initial examination of the existing furniture indicated several anomalies in the design of the classroom benches and desks such as lack of cushion on the hardwood benches, and lack of backrests. Based on several complain of body aches and pains from the children, a survey was conducted to obtain additional information which could be helpful for the research analysis. Findings from the questionnaire showed that a large majority of the 126 first graders surveyed (95%) attended classes more than three times a week and were seated in the classroom for more than four hours daily (93%). Also, 58% of the children acknowledged they had been absent from school at least once in a month due to aches and pains often associated with their sitting postures while in the classroom. In summary, this paper analyzed anthropometric information obtained from the subjects to provide adequate guidelines for the design of adjustable classroom furniture. This was based on the need to reduce the level of mismatch between the first graders and the type of furniture provided for their use. One of the major objectives of this research was to propose ergonomic design guideline for classroom furniture that would accommodate at least 90% of the entire population of elementary school first graders in the United States. Values from relevant growth charts which comprises of stature-for-age and weight-for-age percentiles limits for boys and girls of ages 2 to 20 years old was obtained and incorporated into anthropometric equations (see Equations (5), (6), (7), (8), (9) and (10)) in the quest of obtaining adjustability ranges for the classroom furniture. In order to accommodate at least 90% of the population of first graders, the following dimensions obtained from Table 4, Table 5, Table 6, Table 7, Table 8 and Table 9 are recommended (based on a recommended clearance of ±1 to 2 cm): For seat height (25.83–32.23 cm); seat depth (27.41–33.86 cm); seat width (17.91–23.29 cm); back rest (35.64–44.37 cm); arm rest (16.28–20.68 cm); and desk height (30.12–37.85 cm). Based on the recommended dimensions of the elementary school furniture design for first graders, it will be easier to produce adjustable ergonomics-oriented classroom furniture within the recommended design limits. Even though adjustability could increase the cost of production, a major benefit of incorporating adjustability into the furniture design is the opportunity to increase the accommodation limits. Based on the variability in the body sizes and dimensions of the students, individual classroom furniture for the children is recommended, as this would provide the opportunity for each of the children to adjust their desk/workstation based on their preference or comfort level. This will ultimately enable the reduction of the severity rate of pains and aches experienced by the children. 5.1. Future work and limitations of the study Further evaluations would incorporate additional anthropometric data from other age groups of young elementary school students, from different parts of the world, with more gender mix in the experimental design. More gender mix and other individual differences such as race, age, and more data from multiple elementary schools would have also improved the quality of the experiment. In the future, a comparison of the results obtained in this analysis and the data obtained from ISO 5970 – 1979 and the New British and European Educational Furniture Standard (EN 1729). Although the results of this experimental study show that stature is a good predictor of a number of other body dimensions such as popliteal height, elbow height, etc, efforts could be made to determine other possible predictors such as weight or BMI. In terms of the hip breath, the body weight could have also been analyzed as a possible predictor and the relationship obtained could have been used to compare to that obtained when the BMI was used. Although this study proposed classroom furniture design guidelines to accommodate approximately 90% of the population of first graders in the United States, significant increase in the overall accommodation could have been obtained if further analysis was conducted to investigate the possibility of increasing the height adjustability limits. This would have further provided accommodation for extreme individuals within the population. This design recommended adjustability for all the dimensions of the classroom furniture. Incorporating too much adjustability could be extremely costly which could lead to a difficulty in affordability. The accuracy of the experiment would have also been improved if the number of experimental subjects had been increased.