Teacher:This task is about reading the given passage and construct a question about the information present in the passage. Construct a question in such a way that (i) it is unambiguous, (ii) it is answerable from the passage, (iii) its answer is unique (iv) its answer is a continuous text span from the paragraph. Avoid creating questions that (i) can be answered correctly without actually understanding the paragraph and (ii) uses same words or phrases given in the passage.
Teacher: Now, understand the problem? Solve this instance: Chopin's études are largely in straightforward ternary form. He used them to teach his own technique of piano playing—for instance playing double thirds (Op. 25, No. 6), playing in octaves (Op. 25, No. 10), and playing repeated notes (Op. 10, No.  7).
Student:
What pieces of his did Chopin use to teach his technique?