Final answer:
Miguel should use the most formal language and correct grammar for his project as he is writing a personal letter to his grandparents.
Step-by-step explanation:
The student who should use the most formal language and correct grammar for their project is Miguel.
Writing a personal letter to his grandparents requires a more formal tone and adherence to proper grammar rules. Personal letters often follow specific conventions, such as using formal greetings and signing off with a polite closing.
In contrast, the other students are engaging in more informal communication or projects. Amanda is trying to convince her classmates, which typically involves using persuasive language that may not adhere to strict grammatical rules. Fatima is making a computer slide show presentation, which allows for a more casual tone. Harry is teaching his teammate, which often involves casual language and may not require strict grammar adherence.