Thank you for submitting your homework. I hope you enjoy your weekend with your family. ^_^

Please take notes of my corrections.

Woojung: On Saturday I usally go to my grandparents house with my family and On Sunday I usally go to the church at the morning.

Correct: On Saturdays, I usually go to my grandparents' house with my family and on Sundays, I usually go to the church in the morning.

**EXPLANATION**
~We should put a comma (,) after the introductory element and we should say "Saturdays" and 'Sundays" because you used "usually", so it means that you usually do it on Saturdays and Sundays.

~For possession, don't forget to use apostrophe ('), it is used to  indicate the possessive case. (grandparents' house)

~Don't forget to check the spelling before submitting so that you can have less errors.

Woojung: Last weekend On Saturday I stayed home and On Sunday I went to the Grandparents house with my mum.

**EXPLANATION**
~Avoid redundancy. Don't forget to use commas, too. No need to capitalize "On" and "Grandparents".

Woojung: This weekend my mum and I will go to Seoul to see my friend Saturday to Sunday.

Correct: This coming weekend, my mum and I will go to Seoul to see my friend.

**EXPLANATION**
~Since you are pertaining to the coming weekend (future) you can just say "This coming weekend," and don't forget to use a comma. We know that "weekend" is Saturday and Sunday, so you can just remove "Saturday to Sunday" to avoid redundancy.