Can anyone explain what में is doing here? Thanks if so!
It's part of " साथ में " which collectively means "together" or "with". Hope that helps.
It does - thank you!
Have I sometimes seen other constructions of साथ, such as के साथ? How do you decide when to use के साथ versus साथ में ?
Using "ke sath" would mean "grandfather is walking with me", as opposed to "sath mein", which means "grandfather and i are walking together".
That makes perfect sense, you're the best, thanks!
Why did it accept my answer without में between सथ and चल? Shouldn't it make a difference in the sentence's meaning if I forgot to put it in?
As far as I am aware, it does not actually make a difference in some cases, this being one of them. Sorry I don't really have an explaination for why that is so.