It was not easy to train students in an industry. What did they hope to teach in Tuskegee?

From the text:

We wanted to teach them what to eat, and how to eat it properly, and how to care for their rooms. Aside from this, we wanted to give them such a practical knowledge of some one industry, together with the spirit of industry, thrift, and economy, that they would be sure of knowing how to make a living after they had left us. We wanted to teach them to study actual things instead of mere books alone.