How to Say "because" in Korean? - 왜냐하면

"because" in Korean is 왜냐하면 (waenyahamyeon)

더워요. (deowoyo) - It's hot.
바다 가고 싶어요. (bada gago sipeoyo) - I want to go to the sea.
그래서 (geuraeseo) - so
더워요. 그래서 바다 가고 싶어요. (deowoyo geuraeseo bada gago sipeoyo) - It's hot. So I want to go to the sea.
그런데 (geureonde) - but
학교 가요. (hakkkyo gayo) - I go to school.
학교 갈 거예요. (hakkkyo gal geoyeyo) - I'm going to go to school.
내일 학교 갈 거예요. (naeil hakkkyo gal geoyeyo) - I'm going to go to school tomorrow.