Cutting up the world

This is an idea for a starter to introduce the topic of food supply. It particularly appeals to visual learners.I use an apple to represent the earth. I then cut the apple into quarters and put three quarters to one side, these represent the oceans of our world. The quarter that is left I slice in half. I put one of these halves to one side. This represents the areas of the earth where people are unable to live or work on. The poles, deserts and very mountainous regions. An eighth is what is left this represents the area where humans live. I then slice that section into four sections and up aside three of them. These sections represent the places where the soil is too poor to farm - where it is too rocky, wet, cold or steep to produce food. They also represent urban areas, where we choose other land uses. The final 1/32 that is left is the farmable area of the earth on which humans are totally dependent.Once I have completed the demonstration pupils can draw a diagram or pie chart to show the results. This is a great way of numeracy in a lesson too.