SO

1.-I had an early meeting at work so I had to get up early

2.-I`m hungry so I`m cooking dinner    

3.-She wants to speak spanish so She takes evening courses

4.-We needed a vacation so We went to the seaside

BECAUSE

5.-They`re going to visit us soon because We haven`t seen them in along time

6.-I went for a walk because I needed some fresh air   

7.-He bought a new house because Jack won the lottery

8.-They bought a CD because Their friend had a birthday