This detailed lesson helps students fully understand economies of scale. The lesson starts with a fun 'How Big' starter worksheet - this is where students have to guess the different sizes of large companies (answers included). The lesson then looks at how large companies can benefit from economies of scale. The lesson covers the economies of scale diagram and how average costs fall as production increases. The lesson also looks at the clear difference between internal and external economies of scale. I have focused many tasks throughout this lesson that helps students fully understand the concept of economies of scale. The lesson also looks at diseconomies of scale in a lot of detail. I have also provided a great task based on Mega Dairies in the UK and USA and how they hope to benefit from economies of scale - this includes a number of great video clips and an excellent worksheet that could be used in a group activity. This lesson could easily stretch across 2-3 hours of teaching. A great lesson which would be perfect for Economics.