Lots of possibilities, including “happy” music originally composed for children. I’ll suggest a number but this topic can easily bloom into a collective project:
Poulenc: The Story of Babar, the little elephant/Histoire de Babar, le petit elephant (the French and English versions are available on Naxos 8.553615F -- “Poulenc Complete Chamber Music Vol. 5.” It involves a child narrator)
Debussy: His Children’s Corner (piano and orchestrated) includes revealing piece titles such as Doctor Gradus ad Parnassum, Jimbo’s lullaby, Serenade of the doll, the snow is dancing, the little shepherd, and, my favorite, Golliwogg’s Cake-Walk, a very happy piece..
Ibert: He often wrote happy-going music. In his “Histoires,” based on fairy tales, one finds quite an emotional range for kids from the very happy “Little white donkey” to the very sad “Dans la maison triste.” Perhaps you could use these small piano pieces to show how classical music expresses many different feelings, a bit like fairy tales.
Ravel: For a man who never married and raise children, Maurice Ravel proves a magician when it comes to music involving or aimed for children. Lyrics may prove a problem if you teach in Spanish (curious, isn’t it, given that Ravel’s mother, Marie Delouart, was Basque) but his music to Jules Renard’s “Histoires naturelles” still amazes me: the peacock, the cricket, the swan, the kingfisher, the guinea-fowl (hilarious). Do you think your children are ready for a soprano or a tenor voice accompanied by a piano? If not, perhaps you can find the music without its vocal element.
Enough said. I’ll yield the way to other suggestions…..
No, can't help myself! Another suggestion:
Prokofiev: Peter and the Wolf is an excellent and lively work which uses an interesting story to help children identify various instrument solo and groups of instruments in the orchestra.