Design to Learn: Constructing Tangible Symbols
Tangible Symbols should be constructed for each individual user, capitalizing on the features of the referents that are most meaningful to the individual. If the symbol does not have a connection to the referent that is clear to the user, then it is not tangible to him. For that reason, Tangible Symbols are not pre-made and marketed. If you used ready-made symbols, you'd have to assume that the symbols represented something motivating to any user, and also that the relationship between symbol and referent was obvious to any user. Both of these conditions are unlikely.
Three-dimensional symbols may be identical objects, parts of objects or associated objects (such as a straw for "drink"). Suppose you're deciding how to make a 3-dimensional symbol for a particular toy that a child highly prefers. Pay attention to how the child plays with it. What does he focus on? Does he hold the toy by the handle? Does he pull the string or push down on the lever to activate it? Is he focused on the red arrow that spins?
By making a symbol that is similar to the features of the toy that the child focuses on, you create a symbol that is immediately meaningful to him. For instance, a pull string from a broken See 'n Say might be a good symbol for that toy if the child independently uses the string himself. Or a handle bar grip might make a good symbol for a bicycle. Note: miniature objects are rarely useful symbols, especially for people with poor vision.
Two - three dimensional Combination Symbols
For certain children it may be necessary to combine two levels of representation. For example, an individual with some usable vision might be quite reliant on tactile information and tend not to use her vision. In this case we might combine a photo image with a 3-dimensional representation of it on the same card, increasing her exposure to 2-dimensional representations, but at the same time leaving her access to a symbol type that is readily understandable. The photo is placed at the top of the card so that when she tactually scans the 3-dimensional portion the photo is not obscured. Over time, we could reduce the tactile information provided by the 3-dimensional portion of the symbols as much as possible.
When taking photos for symbol use, it's worthwhile to attend to the amount of background "information" that you include. For some people, a picture of the referent in the context it's associated with is a meaningful symbol. For another person, the background should be a solid neutral color, contrasting in color to the referent pictured. The backgrounds used across different photos should be similar, so that when the child chooses from an array of photo symbols you know that he is responding to the image and not to the colored background.
Specific Line Drawings
These 2-dimensional representations are line drawings of referents. They are specific, meaning that they look exactly like the actual referent used, rather than a generic version of it. The drawing of the toy car looks just like the toy car, not just any old car. Photographs may be traced and then photo copied onto regular paper and sized to accommodate the user. They may be colored like the referent.
Generic Line Drawings
These are the 2-dimensional images available through commercial sources. For those who can use this level of representation meaningfully, it's easy to keep up with their growing vocabulary. Pictures may be photocopied or printed off the computer using specially designed software. These images are generic in that they do not, in most instances, look identical to the actual referent . With the exception of color that you may add, the car picture may not be the specific configuration of the user's actual car.