contorting

"My mother taught me good posture for sitting at the desk during school. "

"The instructor explained the new math concept clearly to the students. "

"Her most striking features were her bright blue eyes and high cheekbones. "

"After school, I like to eat a salty pretzel while I do my homework. "

"The teacher advanced the students' understanding of fractions by using visual aids. "

"The little girl strained her teddy bear to her chest, comforting herself after a bad dream. "

"The violent assaulted the student in the school hallway. "

"Can you demonstrate the new tools for us?"

"The twist of the metal rod caused the gears to turn. "

"My sister's joyful expression showed how happy she was about the good news. "

"features contorted with fury."

"My sister learned to write in a very careful manner. "