Commonlit has free literacy resources and progress tracking tools plus hundreds of fiction and nonfiction reading passages for grades 5-12.

iPad App for Persuasive Writing

Mars Gen One: Argubot Academy is an iPad role-playing game that illustrates the purpose of making a solid, evidence-based argument. The app uses STEM-themed issues while learning about the components of a valid argument.

ReadWorks Digital

The nonprofit ReadWorks provides K-12 teachers with what to teach and how to teach it—online, for free, to be shared broadly.
They provide the largest, highest-quality library of curated nonfiction and literary articles in the country, along with reading comprehension and vocabulary lessons, formative assessments, and teacher guidance. Most importantly, everything ReadWorks does is based on proven cognitive science research.