Therefore, this is really just a brief introduction to the chunking technique, which should be extended to many practice paragraphs, to complete essays, and ultimately used in all writing across the curriculum. Chunking is taught in many AP composition classes, in which the students must learn to write something meaningful, and do it fast. We need a Coke machine in our school. Most other schools have Coke machines, but ours doesn't. All we have to drink here is water, which tastes terrible, from fountains which often don't work.
Students are here eight hours a day, with nothing to drink but water.
Teachers have a Coke machine in the teachers' lounge, but students aren't allowed to use it. Something is wrong with this paragraph. It's pretty obvious what the writer wants, but after about the first sentence it doesn't seem that he cares very much. He's not very convincing. His main problem is that he's just giving us a series of facts that seem to relate to his topic, but there's no explanation, no argument.