Final answer:
The German school of composers contributed to the symphony by adding a minuet movement.
Step-by-step explanation:
The contribution to the symphony made by the German school of composers is the addition of a minuet movement. The German composers of the Classical and Romantic eras, such as Mozart, Beethoven, and Brahms, often included a minuet movement as the third movement in their symphonies. This movement is typically in triple meter and has a dance-like character. It provides a contrast to the more serious and dramatic first and second movements of the symphony.