bouncyballs.org is a great noise monitor for educators! During center rotations, partner/group work, and games you can have students monitor their own noise level by projecting this website. One of the best things about this tool is you can adjust the sensitivity of the noise to suite your comfort level. I also love that you have the choice to change what "bouncy ball" you are using (choose from eyeballs, bubbles, plastic balls, or emojis)!!