Maycee Wieczorek, a 17-year-old in Rapid City, S.D., said it felt odd as a student to hear grown-ups dismissing the significance of Mr. Kavanaugh’s character in high school.

“For me and my friends his past is our now,” she said.

And she worried that if the Senate does not take Dr. Blasey’s allegations seriously, it will reaffirm the idea that “boys will be boys,” and teach a dangerous lesson to teenagers today.

“Boys will learn that what you do in high school won’t affect your future at all, so go do the damage you need to do now,” she said.