Minneapolis ABE has links to lessons for English language learners from levels 1 to 6 in reading, writing, listening, pronunciation and vocabulary in a broad range of subjects. Although intended for adult learners, most lessons are appropriate for K-12 students as well.
The site does not have any easy way to navigate the skill levels so use these link:
English Level 1
English Level 2
English Level 3
English Level 4
English Level 5
English Level 6