1. At Sora's school, the first period begins at 8:30 am.

2. The first class begins at 8:30 am at Sora's school.

3. School begins at 8:30 at Sora's school. Students should come to school by 8:30, and they should do self-study for 30 minutes. They take a break for 10 minutes. Then the first class begins at 9:10 am.

(Are they all grammatical? Would you check the sentences? Thank you.)

The only correction is that am is an abbreviation so it should be written a.m.

Yes, all three sentences are grammatically correct. However, there are some differences in the way the information is presented.

1. "At Sora's school, the first period begins at 8:30 am."
This sentence simply states that the first period of the school day starts at 8:30 am. It provides straightforward information without any additional details.

2. "The first class begins at 8:30 am at Sora's school."
Similar to the first sentence, this sentence also mentions that the first class starts at 8:30 am. However, it specifically refers to it as "the first class" instead of "the first period." The wording may vary depending on how the school organizes its schedule.

3. "School begins at 8:30 at Sora's school. Students should come to school by 8:30, and they should do self-study for 30 minutes. They take a break for 10 minutes. Then the first class begins at 9:10 am."
This sentence provides a more detailed description of the school routine. It explains that students should arrive at school by 8:30 am and engage in self-study for 30 minutes. After a 10-minute break, the first class begins at 9:10 am. This sentence offers a broader overview of the morning schedule at Sora's school.