flippant

"My younger sister is a teenager now, and she's starting to get more independent. "

"The class squirmed and fidgeted in the uncomfortable new chairs."

"to die by an accident"

"It was a surprise to see the captain, who had always seemed so serious, laugh so heartily."

"I saw a movement in that grass on the hill."

"The hypnotist mesmerized the student, calming her anxiety before the presentation. "

"Everyone in the class needs to bring their textbook to the first lecture. "

"The ballet dancer walked with a graceful attitude."

"His constant interruptions during the meeting showed a disrespect for the speaker. "

"The speaking portion of the exam made me nervous. "

"The rapidity of her typing allowed her to finish the report before the deadline. "

"The teacher emphasized the seriousness of failing the final exam. "