Learn Hardcore Japanese: bunkasai de gyouza wo tukuru ka douka, mada kimatte imasen. - It has not been decided yet whether we will make dumplings at the school festival.

Breakdown of bunkasai de gyouza o tsukuru ka douka, mada kimatte imasen.

What does かどうか mean in this sentence?

かどうか means whether or not.

So:

It turns the clause before it into an embedded yes/no question or uncertainty clause.

A useful pattern is:

Examples:

In your sentence, the thing that has not been decided is exactly this: whether to make gyoza at the cultural festival.

Why is 作る in the dictionary form?

Because before かどうか, Japanese usually uses the plain form of the verb.

So:

This does not make the sentence casual overall. It is just the normal grammar for a clause placed before かどうか.

This is very common in Japanese:

Even if the main sentence is polite, the verb before かどうか is usually plain.

Why is で used after 文化祭?