You can write a story about a city and make an analogy between cell organelles and things in the city that carry out similar functions. For example, a powerplant is like the mitochondria. Factories would be much like the ribosomes which are sites of protein synthesis. The town hall is similar to the nucleus--which has the instructions to control the cell. The golgi apparatus is like the postal service since both package materials to be shipped. Protein is the product that ribosomes manufacture and would be similar to the product produced in the factory. The cell membrane is like a fence surrounding the city. Lysosomes are like a scrap yard and the nucleolus is like the carpenter's union which builds the factory.