Article: 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).

Now answer this question: Chopin often taught his piano technique using what form of music he wrote?
études