"So that" is similar to "so" and "in order to." It expresses reason, and it answers the question "why" something is done. "So that" also expresses to what extent (how much) something is true.
1. She watches a lot of TV during the day so that she doesn't feel so lonely.
She got so lonely that she decided to watch TV. (This describes how lonely she got)
3. Many smart countries are learning how to develop solar energy technology so that they can be less reliant on fossil fuels.
Burning coal is so bad for the environment that many companies are starting to get their energy from the sun.
4. She wrote his phone number on her hand so that she wouldn't forget it.
She likes him so much that she decided to ask him out. (This describes how much she likes him and what she did as a result of her feelings for him.)
5. So that they could save money on plumbing costs and help the environment, my neighbors built an outhouse.
(notice that "so that" can go at the beginning of a sentence -- but usually it doesn't. )
An outhouse is a bathroom that is outside of a house.
Next: Lesson Nine