"We have set a clear goal vital to the next chapter of America's story in space: sending humans to Mars by the 2030s and returning them safely to Earth, with the ultimate ambition to one day remain there for an extended time," Obama wrote in an essay posted by CNN. We give students a clear and logical sense of direction and purpose and it is better to start with a simple, coherent attitude than to ramble aimlessly or produce a shapeless answer.