Listen to two very different pieces of music as a starting point. The opening allegro non molto from Vivaldi's "Winter" (last of "The Four Seasons") evokes the bitter cold through its F-minor key and its dissonant harmonies, while the chill winds seem to feature in the swirling violin arpeggios. Debussy's piano prelude "Des Pas Sur La Neige" (Footsteps in the Snow) creates a bare landscape - a slow stumbling ostinato rhythm underpinning a sighing melody.
Children can adapt Debussy's shaping idea to make a picture of someone trudging through heavy snow. Use a short tentative scrap of rhythm and repeat it slowly to sound like unsure footsteps; over the top of that, play a melancholy tune that sounds as if the journey will become harder and sadder before it finishes.
Pupils can try their own version of Vivaldi's idea of contrasts between slower and faster sounds. They can invent a listless chord progression with minor keys and decorate it with surging arpeggios - stillness and movement, nullity and energy together.
Look more closely at the extraordinary emotional power Debussy packs into his miniature piece. What expressive use does he make of the recurrent appoggiatura? How does the desolate fragmented melody anticipate the language of later 20th-century composers?