In addition to being quite possibly the best free introduction to CS and programming available online, it also has sequel courses in web development, AI, and game development that one could take.
Alternatively, or in addition, you could follow this course with NAND to Tetris, which had its second addition come out last year and will give any student a firm foundation in understanding lots of low-level details with project-based learning that only requires some basic programming skill.
I cannot recommend it highly enough.
And, if you don't care for the certificate at the end of the course, it's free