Hello, fellas. In this session we will learn how to express using so that.
Like in order to, so that expresses purpose. The word that is often omitted in speaking.

Example:
I turned off the radio so (that) my friend could sleep.

When the idea of ability is being expressed, so that is often used instead of in order to. Can is used in the adverb clause for a present/future meaning. Furthermore, could is used after so that in past sentences.

Examples:
1) I am going to earn money so that I can buy the book.
2) I earned money so that I could buy the book.

Sometimes, the simple present is used after so that in place of will. It carries a future meaning. Would is used in past sentences.

Examples:
1) I will have a breakfast so that I will not be hungry.
2) I will have a breakfast so that I am not hungry.
3) Yesterday I had a breakfast so that I would not be hungry.

Source:
Betty Schrampfer Azar, Understanding and Using English Grammar: Third Edition