Simplicity is not overrated, and restriction breeds creativity. Polotno Studio doesn’t have pre-made templates, nor does it have a wide selection of tools. What it does have is a load of photos and graphics that you or your students can use to create graphics. The site allows you to save your creation to your local machine. This is important because the site has no concept of accounts.
One of the best features of the site is that it doesn’t require accounts. Students can navigate to the site and can immediately start creating. Polotno Studio can also be used to teach the concept of opening and saving, which is becoming a lost skill in the era of online, auto-saving, services.