"수학여행으로 어디 가?"

Translation: Where are you going on the class trip?

[mxriii]

I thought it was maths trip

[stickyrenice]

Me too. Because 수학 means maths

[AbeVallerian]

Shouldn't it be 어디에?

[josueetcom]

Generally speaking the -에 particle (like some other particles) can be dropped if its role is implied so 어디에 can be simplified to 어디. Fyi, 어디에서 is often simplified to 어디서 too.

[army23600]

Duo started teaching the casual instead of polite.....

[llewellyn.1]

Wouldn't you say "Where are you going for the class trip?"

[Jweg61]

Both "on" or "for" are cool in English in this case, also okay would be "during" (but the Korean might change to be more specific there),

[SvedishPlumber]

Shouldnt this be in the future tense?

[roberto727]

It's common to use present tense for future plans just as we do in English.

What are you doing tomorrow" 내일 무얼 해?

Where are we working next month? 다음달에 우린 어디서 일해?

Is she throwing a party after graduation? 그녀가 졸업식 후에 파티를 여러?

[DonatienLO]

Do we have to say "the" class trip, couldn't we say "on class trip"?

[Sarah610755]

No, the article is required in this sentence.