The most elemental answer here would be that you could always strive to purchase the lesson plan for Boyne's work on enotes. This lesson plan has been written by teachers and collaborated on by educators, so there is a level of credibility in this online lesson plan. Vocabulary lessons are included in this lesson plan. This would be one location if you wanted to find a pre- made lesson plan regarding vocabulary for teaching The Boy in the Striped Pajamas.
I do think that you could construct your own lesson plan regarding vocabulary acquisition. One approach to take would be to teacher- generated in which you, as the instructor, would find specific words and ask students to engage upon different tasks with the words. Some of these could be to define them or use them in a sentence. If you wanted to develop a more challenging task, you could ask them to relate said vocabulary items to the time period of the Holocaust and World War II. You could do this for each chapter or as a whole for the book.
Another way to approach vocabulary acquisition is to have the students identify words that they deem to be important. For each term, students could explain its meaning and how it enhances some aspect of the story. For example, how does a particular word describe the tension that Bruno feels with Lt. Kotler, or how does a word function in describing the friendship between Bruno and Shmuel. Having students choose words and then match them up with particularly connotative meanings from the text would enable them to gain a firmer grasp of vocabulary as well as develop a deeper appreciation for the craft of writing in ensuring that there is an understanding regarding why an author would choose specific words for intended effects. In a teacher directed vocabulary exercise or in a student directed one, vocabulary exercises for The Boy in the Striped Pajamas would enhance language acquisition and enhance the connection between reading and writing.