What is Shad's plan for Jethro's future? What does he want Jethro to do? Chapter 3-4

The time Jethro spends with his teacher Shadrach is pleasant and educational. Shadrach and John will be leaving for the Union army the following week. After reading Tom's letter, Shad draws a map of the country, states and various landmarks for Jethro to follow so that he can picture the places mentioned as the news of the war trickles in. Shadrach gives Jethro a thorough accounting of areas of strength and weakness to both sides, during which he is also teaching the young boy the proper use of grammar - throwing in a lesson on respect such as the use of 'Mr.' when referring to Abe Lincoln.