In middle school, many of the teachers are more comfortable introducing more sophisticated and controversial ideas in literature, history, current events, etc., which lend themselves to work products that differ in the level of insight/understanding/analysis. The assignments are also more open-ended in the sense that a student may choose to do more research and/or produce a lengthier or more complex product. The benefits are that the different levels of abilities are more apparent in the final products, the students may be challenged to think through and formulate his position, and choose put in the time/effort to produce a better product.