The cell wall provides the division between cells and structural support. In terms of a school, the walls of the building are very similar. Walls divide adjacent classrooms and provide structural support for the roof.
The chloroplast is a little more difficult to relate to a school. Chloroplasts are intracellular organelles where photosynthesis occurs in plant cells. Photosynthesis is the conversion of sunlight into sugar, which the cell then consumes for fuel. Perhaps the lunchroom is a good analogy? In the lunchroom, cooks convert raw ingredients into lunches which the students then consume. This food is the fuel their bodies need to function. You could also use the boiler room as an analogy. In the boiler room energy (in the form of gas) is used to produce steam which then warms the building. The main thing to remember is that the chloroplast is the site of energy conversion.