This paper aims to develop a teaching material, using Carroll's Through the Looking-Glass, and What Alice Found There (TLG) as its source. Chapter 6 of the book comically shows us what Humpty Dumpty thinks of words. Humpty Dumpty says to Alice, 'When I use a word... it means just what I choose it to mean- neither more nor less.' In short, Humpty Dumpty 'is to be master.' This relationship between Humpty Dumpty and words is in stark contrast to that between people and language hypothetically pointed out by two linguists, Sapir and Wharf. The Sapir-Whorf Hypothesis, according to which language controls our thought, is dealt with in a senior high school English textbook. We claim that the lesson on the hypothesis can be effectively taught with a passage from Chapter 6 of TLG. To help students read TLG in the original, 12 comprehension questions are also suggested in this paper. In addition to TLG, a passage by Yasunari Kawabata might enhance students' understanding of the Sapir-Whorf Hypothesis as well. The passages from TLG and Kawabata would contribute to 'deepening [students'] understanding of language and culture' - one of the three objectives of learning foreign languages articulated in The Course of Study.