Speak is an extension for Chrome that performs text to speech.
You may already know about Speak-It, but it has two issues that may not work for you in your district. One is the fact that is free for non-commercial use only. Does a school district satisfy that requirement? I don’t know. The second is that all of the requests are sent to their server for processing. This adds to your bandwidth usage in your district and could have privacy implications.
Speak is an open source extension for Chrome that is definitely free to use and uses local text to speech. Once the extension is installed, clicking on a paragraph in a webpage will start it talking. You can adjust the behavior of the extension through the toolbar icon.