From Arts & Letters:
Rub-a-Dub was developed as a tool for teaching basic computer skills to young children.Beginning, as early as age three, children are able to relate the movement of the mouse in a horizontal plane with the movement of the cursor in a vertical plane on the screen. Once that association is mastered, further progress using a mouse is rapid, although the issue of hand-to-eye coordination is paramount. The cornerstone of the Rub-a-Dub concept is the Rub tool. The Rub tool is activated by holding down the left mouse button and moving the cursor in the image area. Doing so reveals portions of a second image that is stored in a layer beneath the original image. If the image on the screen is a black and white line drawing, using the Rub tool causes colors to appear as if by magic. If the image is already colored, additional detail may emerge or the colors may change as in spring to winter or day to night. Using the Rub tool to color combined with the element of surprise in discovering hidden imagery appeals to childrenÃ¢??s curiosity. Moreover, it is a simple process requiring minimal skills and yet yields results that sustain their interest. Obviously, the content of the images plays an important role in the entertainment value of the process. To further enhance the process, the Rub tool is coupled with the Windows Midi sound player. A background musical theme plays whenever the Rub tool is moved. If the child stops, the music stops and then resumes when the Rub tool is moved. This interaction of the music with the Rub tool to signify something different is happening reinforces the visual association between the cursor on the computer screen with the movement of the mouse.