Hi Yikang,

The NGSS Biology course is aligned with the Next Generation Science Standards and is currently designed to be used as a supplement in NGSS classrooms and not as a standalone course. If you are enrolled in an NGSS-aligned course in your school district, then this would be a good choice for you. If not, then I recommend taking the standard High School Biology course instead.

You can find more information about the NGSS courses here: https://support.khanacademy.org/hc/en-us/articles/4406030883725

Please let me know if you have any further questions!