Stephen put on his hat and scarf. It was a cold day.
These two sentences can be joined using the word because.
Stephen put on his hat and scarf because it was a cold day.
We can also use the word as to join the sentences.
Stephen put on his hat and scarf as it was a cold day.
We can also join them using the word so, but we have to swap them round to do this.
It was a cold day, so Stephen put on his hat and scarf.
Our writing is more interesting if we use different connecting words to join sentences.
Shall we try some questions?