Final answer:
The word that best describes the mood of the excerpt is anticipation.
Step-by-step explanation:
The word that best describes the mood of the excerpt is anticipation. The narrator paces back and forth, itching to catch a sound of the protesting students with their signs. This implies a sense of eager expectation and excitement. The use of the phrase 'itching to catch a sound' conveys a strong desire to be part of the protest and adds to the overall anticipation.