PetSilence

PetSilence is a free classroom noise monitor and noise meter that runs in any browser and is built for the classroom projector. A cartoon class pet sleeps while the room is quiet, looks up as voices rise and covers its ears when it gets too loud, so students see the noise level without the teacher saying "shh". Teachers can switch to bouncing balls, or to Quiet Farm, where quiet minutes grow a crop and each focus goal is a harvest that builds a class farm over the school year.

Features: focus timers from 3 to 15 minutes, Silent and Whisper zones, room calibration, full screen and an optional too-loud chime. No sign-up or install; it works on Chromebooks, iPads, Windows and Mac. Classroom audio is processed in the browser and never recorded or uploaded. Made for K-8 teachers as a free alternative to Bouncy Balls.