Hi Gromlo,

The regular Arithmetic course is the recommended curation that is generally best for most learners. The regular Arithmetic course also has Course Mastery enabled, whereas the all content version does not.

The "All Content" courses act as a catch-all for content that is related to the overall subject (Arithmetic) but that doesn't fit well in the standard curation of the course. Thus, there may be some content that appears in the "all content" course but not in the regular version of the course (and vice-versa). Unless you're specifically searching for something that's not in the regular version of the course, the regular version is probably the best choice.

I hope this helps! Please let me know if there's anything else I can do for you!

Thank you very much.

I got it and I think the first two lines of your reply would have cleared the the doubts and had it been a short note at the beginning of the two courses. Adding an explanatory line or two before each course will be of great help.