Purdue Online Writing Lab (OWL) –
This is a free online writing resource is provided by faculty and departments at Purdue University, and can help students with improving their writing skills with attention to grammar, styles, research, and appropriate citations.
Purdue Online Writing Resources for Grades 7-12 (OWL) –
This is another free online writing resource provided by faculty and departments at Purdue University, which specifically addresses the writing skills and learning needs of 7-12 school students.
Khan Academy –
“The Khan Academy is a free online education resource and offers practice exercises, instructional videos, and a personalized learning dashboard that empower learners to study at their own pace in and outside of the classroom. They cover topic areas in math, science, computer programming, arts and humanities, economics, standardized test preparation and more.”