Co-writer -- offers a more robust word prediction tool that can predict based on phonetic spellings for those students with significant spelling difficulties; downloadable topic dictionaries, custom dictionaries. Co-writer tutorials Free account for teachers. Request a license by using the form here.
Read and Write offers a variety of reading and writing tools.
To work with PDFs and images on the iPad, try Notability, SnapType Pro or Co-Writer.
Crick clicker apps for both iPad and Chromebook offer three apps that are tiered to advance struggling writers. These apps can be used not only for writing, but also for word skill practice. The app is called "Clicker Writer" and it includes all three apps bundled within it: Clicker Sentences, Clicker Connect, and Clicker Docs. For more information, you can also visit their web page.
EPIC!
TarHeel Reader and TarHeel Shared Reader
RAZ Kids - grade level 1-3
Reading A-Z - grade level
News ELA - K-8 or older
EDMARK
ALL Curriculum
Unique Learning Systems (includes New2You)