Answer:
Across the room, your classmate opens his mouth wide, takes a deep breath in, and exhales. Before you know it, you find yourself yawning too. While scientists do not yet know exactly why yawning spreads from person to person, the experience of "catching" a friend's yawn is one that many can relate to.
Step-by-step explanation:
From the given sentence, I have been able to fix the error that I discovered in the sentence.
From the sentence, I discovered that there is an error in "...you find yourself yawning to". So, we will change the "to" to "too" in order for the sentence to be corrected and fixed.
So, it becomes: "Before you know it, you find yourself yawning too".