MathsNet and NRich Maths 3D shape resource heaven
MathsNet have a wonderful collection of 3D shape resources at this webpage. There are a variety of interactive applets that cover 3D shape topics including nets and 2D views of 3D shapes.
My particular favourite is ‘Building Houses 2’ where pupils have to build the 3D shape by using the 2D views given. They score maximum points by using the minimum number of blocks possible. By clicking and dragging on the 3D view pupils can spin their construction around in real time to help them with the task.
NRich Maths have a superb and challenging activity based on 2D views of 3D shapes called The Perforated Cube. Pupils can use the Building Houses 2 applet to help them with the investigation which is based around a cube made from 125 smaller cubes in a 5x5x5 arrangement. The cube has ‘mini-cubes’ removed to cause perforations. Pupils are given 3 2D views of the shape and have to calculate what is the maximum and minimum number of mini-cubes required to give those views. Highly recommended.
UPDATE: MathsNet seems to be history, but the same links are available from this site: http://mathandmultimedia.com/2012/03/02/3d-math-applets/