Writeacher, could you please check the very last things. It's really late here and I need to go to bed. Thank you.

1) Unfortunately, we have just sent in our Comenius proposal for a science project on biodiversity in water with both a German and a French school.
2) However, being an English teacher myself, I would (very much) like my students to be involved in an email partnership and subsequently in a student exchange programme with an English school.
3) In addition, my students will have to learn a subject in English, probably science, in their last year of high school; therefore, they will profit a lot from a partnership between our schools.
4) I was thinking of including about 20 sixteen-year-old students who are preparing for their PET certification...
(We have already corrected this part).

By the way, do you use a "coloured pencil" or a "pastel" when drawing on paper?
A red coloured pencil OR red pencil

a black ball-point pen

1) Unfortunately, we have just sent in our Comenius proposal for a science project on aquatic biodiversity with both a German and a French school.

2) However, being an English teacher myself, I would very much like my students to be involved in an email partnership and subsequently in a student-exchange programme with an English school.

3) In addition, my students will have to learn a subject in English, probably science, in their last year of high school; therefore, they will profit greatly from a partnership between our schools.

4) I was thinking of including about 20 sixteen-year-old students who are preparing for their PET certification...
(We have already corrected this part).

By the way, do you use a "coloured pencil" or a "pastel" when drawing on paper?
A red pencil

a black ball-point pen

Sorry this took so long. I take care of grandchildren in the late afternoons until their mom or dad gets home from work.

I saw very few errors in your writing, and the ones I changed are truly minor! If you sent the email before I posted this, it's all fine. =)