I use this activity to show that as regular pyramids increase the number of sides in their base, the closer they come to acting like cones. It can easily be created using a Microsoft Excel spreadsheet.
This is also a great activity to do when you have a substitute.
If you like this product, you might also like the following. Check out these links.
Surface Area and Volume of Triangular Prisms
Surface Area and Volume of Regular Triangular Pyramids
Surface Area and Volume of Right Rectangul