[Vocabulary] After this or after that: any difference?

[englishhobby]

Here's an extract from one of my students' homework. I got a little confused with "after this" versus "after that". I am not sure if we can use either of them in the following context. (I was going to correct it to "after that", but then I began to doubt.) The student is telling about her last weekend.

In the morning my mom cleaned the bathroom and my father helped her. After this I helped my mom with the cooking.

 

[Rover_KE]

'After this' is OK, but 'After that' is much better.