How should I write a slogan to the effect of "no loud noises in the classroom"?

Silence is better than sound at this time, be careful when you raise your voice and become silent

Please do not raise your voice, don’t startle others (or readers)

Tranquility creates harmony and beauty,

Quietness is a kind of beauty, silent beauty.

Quiet fantasy is the dream of an angel.

Quiet and elegant.

If you dare to speak loudly, Confucius will wither his beard

I hate people who speak loudly, they have no technical content at all.

Flowing water is ruthless and people are affectionate, please let the building be quiet

Heart-to-heart communication requires listening quietly

If the water is not deep, there will be dragons. ; Don’t make your voice too loud, just make it sound

In class, be louder;

After class, be quieter.

Your soft words are a sign of respect for everyone.

In the future, let us cheer loudly.

Today, let us read quietly.

Don’t speak loudly, don’t scare the students

Quiet! net! respect!