Mostly it is because the student is using the mobile version of the site, to allow the browser to record your voice in Burlington English you need to follow the instructions bellow for Chrome or Firefox browsers:
Request Desktop Version of Website on Chrome
Follow the steps below to request desktop version of websites on your Android Phone, while you are using the Chrome browser.
1. When you are in the Burlington English site, tap on the 3 dot Chrome icon, located in the top right corner of your screen
2. From the list of options, tap on Request Desktop site option
From now on all website will be loaded in the desktop version, however you can easily disable this by following the steps below.
1. Open up Chrome browser on your Android Phone or tablet
2. Next tap on the 3 dot menu icon
3. From the list of options, tap on Request Desktop Site
You can also disable the request desktop site feature, by closing the current Chrome tab and opening a new tab.
Request Desktop Version of Website on Firefox
Follow the steps below to request desktop version of websites on your Android Phone, while you are using the Firefox web browser.
1. When you are in the Burlington English site, tap on the 3 dot icon, located at the top right corner of your screen.
2. Next tap on Request desktop site from the list of options.
Similar to the Chrome browser, the Firefox browser will also display the desktop version of every site you visit from now on, unless you disable the Request Desktop Site feature by following the steps below.
1. Open up Firefox and tap on the 3 dot icon
2. Next, tap on Request Desktop site to remove the check mark and turn off Request Desktop Site option.
Request Desktop site feature also automatically turns off when you close the current tab on Firefox and open a new tab.