By using movements from the sonatas of other composers, the young Mozart seems to have begun to learn how to cope with the structural problems of composing in the piano concerto form. Indeed, it may be that Leopold Mozart had devised this as a compositional teaching method. If so, it seems that this may have been the first time this had been done by the composer. This is perhaps supported by two facts: First, Leopold excluded the first four concertos from his 1768 list, suggesting that he may not have considered them true compositions by his son. Second, the autographs of the four works are the joint products of both Mozart and Leopold (although K. 41 is mainly in Leopold's hand alone).