Newsela (www.newsela.com) is a great free resource for articles and text sets written for classroom use. You can change the article’s reading level with a click. There is a writing prompt and quiz to go with each article again customized to the selected level.
You can also create a class and assign texts and reading to your class or individual students. This would blend well with Google Classroom.
There is a paid version that gives you reports on student progress and such but for the most part it is free.