There is a strong case made in Hard Times that education is not simply the classroom experience of memorizing facts. The novel expresses the view that having an emotional component to our education is crucial. It's also shown in the novel that this kind of learning can happen at any time in life. Learning about the way other people live is the groundwork for valuing them as fellow creatures; learning about them only in terms of their productivity is a recipe for class warfare. If this proper groundwork is not laid, then a perverted kind of learning can take its place, full of cynicism and misanthropy.
In the novel, learning is not a lifelong process. Whatever you don't master at a young age can never be taught in adulthood.
Sissy's quippy, Biblical retorts to the teachings of Mr. Gradgrind and the M'Choakumchilds sound good in the novel, but if followed on a grand scale would create anarchy, chaos, and national disaster.