I have always wanted to attend this amazing summer program and this scholarship will provide me this opportunity. I am a science student and I really love science. I am among the top students in my class and I have got exceptional grades in O'levels(This does not necessarily make you unique.) . This scholarship will enable me to further advance my knowledge in this field. I am most interested in engineering preparation program as it will provide me with insight on different engineering fields and help me select one when I get into college. The curriculum taught in this program will give me a foretaste of the topics covered in college. Apart from this, I will improve my spoken English skills as I will get a chance to interact with students from all over the world. Moreover, I will be required to follow the schedule on my own which will create a sense of responsibility in me and make me well organized. Overall this program will provide me with a lifetime experience of a college life.
New one-sentence summary: "I want to go to this summer program because I love science, I'll be prepared for college, and I'll improve my English skills."
It's better, but I think you're going about conveying excitement in the wrong way.
Example of what I mean:
School, soccer practice, homework, cello lesson, hours-long Trivial Pursuit battle with my little sister. I fall into bed exhausted every night, and I wouldn't have it any other way. I am excited to attend your summer program because instead of watching television all day during the summer, I will be watching French films in the European cinema class and talking to teachers and students about the best technique for drawing a face.
It's not perfect, and it's just a snapshot, but you want to tell readers about
you: what you like to do and why you would rather go to this summer program than go swimming or play video games or something.
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As for your second question, think about personal traits, skills, or hobbies. Are you creative, so you'll be able to think of fresh ideas? Do you talk a lot, so you can turn a group of strangers into friends easily? Are you good at any [sports] (sports is just an example that you can replace with anything), and what have you learned from it that will help others? You say you aren't very good at English, so maybe you have an unusual cultural background and a different perspective that can contribute.