Pyramids can have bases of different shapes. 3-D shapes GM3.3 Core Plenary Pyramids can have bases of different shapes. Find a connection between the number of sides of a pyramid’s base and the total number of faces it has. Preamble This activity encourages pupils to visualise the shapes, with the help of diagrams (however these are smaller than they might be, so as not to give too much help). Some pupils may not have realised that pyramids do not have to have square bases. After the rule has emerged, it would be useful to help pupils see how the pattern is built up each time another side is added to the base. Possible content Visualisation of various pyramids. Resources None. Solution/Notes The number of faces (including the base) of a pyramid is one more than the number of sides of the base – a particular case of Euler’s rule.