This is a free language learning app. 

With this app, English Language Learning students can have access to a variety of easy to use, colorful, and engaging lessons to help support their comprehension and understanding. Duolingo can allow a student of any language to start with simple repetitive lessons that will increase in difficulty according to their own pace. Students can practice grammar, vocabulary, pronunciation, and understanding. The app includes reading, writing, and speaking activities, supported by short and long readings, videos, and recordings.

There is also a paid premium version.

Hypothesis is a free Google Chrome extension that allows students to annotate any page on the internet. 

Hypothesis is a collaborative resource that allows teachers and students to interact with one another on the same texts. Teachers are able to post materials where students can collaborate in discussions with one another directly on the document. I would also recommend using Hypothesis to grade annotations and measure student understanding.

The goal of LiveBinders is to help educators and their students go paperless with digital binders. 

Users can save articles and videos, take notes, and post other forms of content in one place. They can also share binders with each other and collaborate to create something useful. With this tool, you never have to limit yourself to just one textbook or resource. You can keep all of your resources in one place for years to come, always adding when you find something new.