Joe and Clement are to people who had many ideas on sustainability and taught us many vital ideas on this subject.
One topic they were discussing about was how we only have 1/32nd of the whole earth to grow our food. this also relates to our maths because our teacher told us to see if they're right, (and if they're wrong we need to prove it with percentages and fractions).
Another subject they were talking about was worm farms and how they help the enviroment so much. The reason worms are so effective to the enviroment is because they will eat your scraps of food besides citrus (e.g. oranges and manderines) and that will cause the worms to run away. 33% of our garbage/ litter thrown out is food, so if all of us have worm farms in our backyards well be saving 33% of our garbage having no food in our dumps (giving more space for us and more time to create more ideas towards sustainability).