Pushed by the semiconductor industry to achieve greater speed and func
tionality, device dimensions are becoming sufficiently small to exhibi
t prominent quantum mechanical effects, In addition, devices are now b
eing developed that utilize these quantum effects, The number and dens
ity of states are fundamentally important in the operation of any quan
tum device. Traditionally in a classroom setting, one dimensional (1-D
), two-dimensional (2-D), and three-dimensional (3-D) continuum approx
imations are presented to analyze the quantum wire, well, and box, res
pectively, As shown in this paper, the exact number and density of sta
tes can be straightforwardly calculated by students for real semicondu
ctor quantum structures. These results clearly illustrate the overall
true 3-D form of each of these structures, These correct calculations
also reveal an overestimation in the number of states when using the c
ontinuum approximations.