This interactive whiteboard resource is useful for demonstrating the volume of cubes and cuboids.
It is a variant on this isometric interactive whiteboard resource. Suggested in one of the comments was to add some more shapes to teach volume. So that resource has been reworked to suit teaching volume. There are number of different cube and cuboid shapes that can be exploded into their constituent single unit cubes. As there is no need to be restricted to an isometric perspective for volume, clicking and dragging anywhere on the screen will rotate the shape. New shapes can be selected using the arrows at the bottom.
Note that as with all of the resources that use 3d this may slow down your computer.