I use Pearltrees primarily for my elementary school students. Ive tried a number of other visual bookmarking tools (Evernote, educlipper, Symbaloo, and others). Evernote is hands down my favorite app, but you cant use the web version on the iPad and I cant download apps on the student iPads. I didnt like the educlipper interface, web or mobile (Im not a fan of Pinterest) and it kept crashing on me. Symbaloo prioritizes smaller tile sizes, so the names of the bookmarks are short and you cant screenshot the site or file.
Pearltrees shows the clipped site, is easy to use in both web and mobile versions. It is similar to Evernote, except that it can be cured mobile devices without the app. I can also share the pages without my students needing to sign up or sin in. This will be my go-to bookmarking app for school.