The sequence of development as hypothesized by Piaget has been confirmed for various groups of children by cross-sectional and longitudinal studies. Such consistency has increased interest in constructing scales based on Piaget's theory according to psychometric principles. Three major problems are discussed which present definite obstacles in the…

In order to identify orientation and mobility skills essential for young blind children, a master list of skills was compiled from developmental studies and teachers' observations and formed into a scale comprised of 47 subscales, each of which had three or more items arranged in developmental order. Scaling was done by jury judgment and by full…