I urgently need you to check these sentences for my Comemius project!!!

I know it is long but what I need to say is quite complicated. I really hope you can help me.
Tell me what you think of the project.

1) I'm terribly sorry I didn't manage to write you before but I've been very busy both at school and at home.
2) Actually, I'm not going through a very nice time since my child has just recovered from a bad flu and my has nearly lost her voice and is going to be operated on her vocal cords next week.
3) By the waw, our science teachers have decided to meet tomorrow to better define the theme and objectives of the project and would like to know a few more things before our preliminary meeting.
4) First, do you still think the project should concern mainly the biodiversity in water and other waterways? Do you believe our physics teachers should be involved in the project as well?
5) Some of our science teachers would like to involve a whole second class of students instead of single students selected from different second classes.

1) I'm terribly sorry that I didn't manage to write you earlier but I've been very busy both at school and home.

2) Actually, I'm going through a bad time since my child had just recovered from a bad flu and had nearly lost her voice. Her vocal cord are going to be operated on next week.
3) By the way, our Science teachers have decided to meet tomorrow to better define the theme and objectives of the project.They would like to know a few more things before the preliminary meeting.
4) Firstly, do you still think the project should concentrate mainly on the biodiversity in water and other waterways? Do you believe our Physics teachers should be involved in the project as well?
5) Some of our Science teachers would like to involve a second group of students instead of individual students selected from different classes.

Do NOT capitalize the S on "science" unless that is a specific name of a course, such as Physical Science 2. The general reference (such as in your sentences) should not have the capital S.

1) The sentence seems to be grammatically correct and conveys the intended message. However, it can be improved by rephrasing it to: "I apologize for not writing to you earlier as I have been extremely busy with my school and personal commitments."

2) The sentence is grammatically correct, but there are a few errors in clarity and punctuation. It can be revised as: "Unfortunately, I am currently going through a difficult time. My child has recently recovered from a bad flu, and my mother has nearly lost her voice. She will be undergoing surgery on her vocal cords next week."

3) There is a small error in the sentence. The phrase "by the waw" should be corrected to "by the way." The rest of the sentence seems fine.

4) The sentence is clear, but it can be improved for better clarity. A possible revision could be: "Firstly, we would like to confirm if the project should focus primarily on biodiversity in water and other waterways. Additionally, should our physics teachers also be involved in the project?"

5) The sentence is grammatically correct and conveys the intended message. However, it can benefit from a slight rephrase for clarity: "Some of our science teachers propose involving an entire second class of students instead of selecting individual students from different second classes."