Khan Academy Science has an amazing set of comprehensive online lessons and quizzes for teaching and testing science.
These Khan Academy science resources are separated into subjects, and perfect for middle school and high school lessons, along with some college material.
Each subject has topic lessons that include videos, sometimes reinforced with articles, and lots of practice exercises, at the end there’s a test section to check your knowledge.
Khan Academy provides these OER resources for improving education standards worldwide.
When students login there is progress tracking available, perfect for monitoring by teachers or parents in school, home school, or extra tutoring.
Sample Page from Khan Academy Online K-12 Resources
Here are the links to each grade level and subject open maths resource provided:
Khan Academy Science Subjects
These are just a sample of the resources, there are many more subjects available at https://www.khanacademy.org/science.
See more Science resources in our Science Category.
See more K-12 resources in our K-12 School Textbooks category.
See more Science books below