Level A1
Subordinating: because (reason)
We stayed home because it rained.
We stayed home because it rained. The reason comes right after because.
Forms
We stayed home because it rained.— because answers why, and the reason comes after itBecause it rained, we stayed home.— the reason can come first, and then a comma stands before the resultIt rained, so we stayed home.— so gives the result, and one linking word is enough in a sentence
A common mistake
Wrong: Because it rained, so we stayed home.
Right: Because it rained, we stayed home.
A common mistake is Because it rained, so we stayed home. One linking word is enough: Because it rained, we stayed home.
More examples
She is happy because it is her birthday.
A reason with because: She is happy because it is her birthday.
It was cold, so we closed the window.
A result with so: It was cold, so we closed the window.