Accuracy of Estimations of Measurements by Students with Visual Impairments

There is a dearth of information about how students with visual impairments learn science-process skills. The study presented here investigated students' concepts and skills in one science area: the estimation of measurements. The estimation of measurements is one of the fundamental concepts that connects all science disciplines that provide the necessary skills to understand the natural world (National Research Council, 1996; Roth & Roychoudhury, 1993) and is an instructional goal at every grade level of the Mathematics Standards (National Council of Teachers of Mathematics, 2000). Estimating is as important in the science laboratory as it is in real-world environments. In the laboratory, students are asked to make measurements using tools, such as rulers, balances, and beakers, all of which typically rely on visual perception. Although adaptive technologies are available to a small sample of students, these tools are not universally available for those who need them in mainstream classes (Jones, Taylor, & Broadwell, 2009a). The purpose of this study was to document the reported experiences of students with visual impairments with estimating measurements, as well as the students' conceptualizations of linear distances and accurate estimations. METHODS Participants The participants were 15 middle school students who were legally blind (9 from birth) (Hollins, 1989). One student had no vision, and the others had low vision (all were braille readers). The participants attended public schools and had been mainstreamed into regular education programs. Of the 15, 3 were girls and 12 were boys (7 were European Americans, 4 were African Americans, and 3 were Hispanics) with an average age of 12.4 (SD = 1.6). The study was approved by the North Carolina State University Institutional Review Board, and consent to participate was given by the students and their parents. Procedures While the participants attended a program on emerging technologies that are designed for students with visual impairments at a large southeastern university, they were invited to volunteer to participate in a research study that was separate from the activities of the technology program. The students were asked a brief series of questions to determine their previous experiences with measurement and estimation: * Have you ever been taught how to measure the length of an object? Please describe your experiences. * Have you ever used a meter stick to measure the length of an object? Please describe your experiences. * Have you ever used measurement tools outside the classroom? Please describe your experiences. * Have you ever been taught how to estimate the length of an object without using a measuring tool? Please describe your experiences. During the interviews, the students' oral responses were recorded. The participants were asked to perform a series of measurement tasks. Test items were pilot-tested with youths with visual impairments to determine their appropriateness for this study. Each of the estimation sizes is typical of those that students would make in middle and high school classrooms. The first task required the students to demonstrate with their hands on a piece of paper a variety of lengths (millimeter, centimeter, meter, and foot). The students' estimates were recorded by the researchers on the paper. The second set of tasks involved the students estimating the length of selected objects using various units. The students first estimated the length of vertical and horizontal dowel rods (91 centimeters, or about 36 inches, long) in both centimeters and inches. The students were given the opportunity to feel the rods that were fixed to the wall to allow them to examine the spatial orientation. Next, they were asked to estimate the length in centimeters of two lines of three-dimensional "puffy" paint. One line was painted on typical white paper, while the other was painted on paper that contained raised dots (providing tactile distracters). …