Deci-Blocks were developed to show how it is possible to use a carefully designed concrete material to do a variety of rich and meaningful tasks. Some concrete materials only have one primary focus and have only very limited values in other areas of the mathematics program. One can easily see how these with the Pattern Blocks can be used to represent all the fractions that are needed; this is clearly one of the strengths of these blocks. As the students use these materials they will undoubtedly find many other ways to use these materials and will gain deep insight into the nature of mathematics.