National Council of Teachers of Mathematics
Nctm: Illuminations: Volume of a Cube
"The volume of a cube can be developed by considering unit cubes, a single row (longs) of unit cubes or a single layer (flats) of cubes using this applet." This easy software makes it possible to easily construct a cube and take it...
University of Cambridge
University of Cambridge: Nrich: Cubes Within Cubes
On this one page website sharpen your logic, geometry, spatial thinking, and problem solving skills while working on this challenge. The solution is available to double check your solution.