Final answer:
The Nutcracker March by Tchaikovsky is known for its consistent marching rhythm and tempo, which traditionally do not change significantly throughout the piece. For a precise answer, the specific excerpt should be analyzed to identify the unchanging element.
Step-by-step explanation:
The question asks about an element that does not change in the excerpt from the song Nutcracker March. When analyzing a piece of music, various elements can be considered, such as melody, harmony, rhythm, dynamics (volume), and tempo. The part of the music that remains unchanged is often referred to as the ostinato, which is a repetitive rhythm or melody. Other features might include the key signature or time signature staying the same throughout the piece. To give a precise answer, one would need to listen to the specific section of the Nutcracker March in question. However, generally speaking, Tchaikovsky's Nutcracker March is known for its consistent, marching rhythm and tempo, which are characteristic elements that typically do not change significantly throughout the march.