Hypothes.is is built to work best on the Google Chrome browser on a desktop/laptop (i.e. a “computer”)
However, there is a work-around for other electronic devices, such as tablets (iPads etc) and phones: go to via.hypothes.is and paste the URL of the article/webpage there. It takes a moment to load the page, but in the top right corner you’ll see the little tab with the arrow icon to toggle the side bar with comments. You can log in and start annotating to your heart’s content.
FYI: Even when I am not explicitly asking you to annotate with hypothes.is, you may use it for any of the assigned readings that are on a webpage. I will check in. (Thank you, students who’ve already done so!)