Learn Turkish: Susarız diye yanımıza büyük bir termos aldım. - I took a big thermos with us in case we get thirsty.

Diye literally means "saying" or "thinking," and here it follows the aorist verb susarız (we get thirsty). Together, susarız diye expresses taking a precaution: "thinking that we might get thirsty" or simply "in case we get thirsty." Using the aorist tense before diye is the standard way to express "in case [something happens]" in Turkish.

Could I use the conditional instead, like susarsak diye?

Yes! Both the aorist (susarız diye) and the conditional (susarsak diye) are commonly used for precautionary clauses to mean "in case." The meaning is practically identical here, though the aorist focuses slightly more on the general possibility, while the conditional emphasizes the specific "if" scenario.

Why use yanımıza instead of bizimle for "with us"?

When talking about carrying items on your person or taking things along for a trip, Turkish uses yanına almak (literally, "to take to one's side") rather than ile (with). So, yanımıza aldım means "I took [it] with us," whereas bizimle aldım would sound unnatural for a physical object you are carrying.

Why is the word order büyük bir termos and not bir büyük termos?