Numbering sections in a two-part paper How do you number the sections in a two-part paper i.e. a paper that is published in two parts?
I wrote an expository paper for high school students and it got accepted into a magazine, only that it will be published in two parts (because the magazine has a limit on the maximum number of pages an article may have). Now, after I have split my paper into two parts, I wonder how should the sections be numbered. The original paper consisted of three sections, which I've split as follows: in part 1 I have sections 1 and 2 and in part 2 I have section 3. Should section 3 still be labeled as section 3, given that it will appear in a different issue? I believe that it should, because I clearly state that part 2 is a continuation of part 1, but I would like to know what the practice is in such uncommon cases.
Should section 3 still be labeled as section 3, given that it will appear in a different issue?

No.  Since the journal/magazine has decided to publish your work in two parts, you should make each part as self-contained as possible.  Number things in a way that will not confuse someone who only has part 2.