Less smart or more dumb?

So I realize that Physics isn't English, but I believe that scientists should be able to communicate well. Two answers found on the same test:

"In colder temperatures, sound travels less faster."
"The microphone is closer to the bat and the sound travels to his TV less slow than it travels to you."

Should I admit that he was one of my English students last year?

Other gems from other students I've had in English class:

"With destructive interference, you can't here it."
"This means he had to go less fast in order to go faster than sound."