Writing prompt: The weekend is coming. Classmates, what are you planning to do? Using the given vocabulary and sentence patterns, and referring to the picture, write a short essay of about 60 words about your plans for the weekend.
Writing hints: be going to; do cleaning; visit grandparents; have a good time

Student essay:
The weekend is coming. I plan to some to sth. I'm going to do my homework with my mother in the morning. I'm going to do cleaning in the afternoon. Second day. I'm going to visit my grandparents in the morning. I'm going to fly a kite in the afternoon. I think have a good time.

Corrected essay:
The weekend is coming. I plan to do something. I'm going to do my homework with my mother in the morning. I'm going to do cleaning in the afternoon. On the second day, I'm going to visit my grandparents in the morning. I'm going to fly a kite in the afternoon. I think I will have a good time.

Error analysis:
error_sentence: I plan to some to sth.
correct_sentence: I plan to do something.
error: some to sth
correction: do something
error_type: Verb Choice Error
error_severity: 4
error_description: ① Verb Choice Error: According to English grammar rules, 'plan to' should be followed by the infinitive structure 'to do'. In the original sentence 〈to some to sth〉, 'some' is not an appropriate verb form and does not meet the collocation requirement of 'plan to', thus it is a verb choice error. 〈some to sth〉 should be changed to 『do something』, which conforms to the verb collocation rule of 〈plan to do〉 and clearly expresses the meaning; ② Pronoun Error: In the original sentence, 〈sth〉 is an non-standard abbreviation, and as a substitute for a pronoun, it cannot clearly refer to specific content, leading to ambiguous meaning, thus it is a pronoun error. According to English grammar rules and expression habits, 〈some to sth〉 should be changed to 『do something』 to make the expression clear and accurate, avoiding ambiguity caused by non-standard pronoun usage.
error_sentence: Second day.
correct_sentence: On the second day, I'm going to visit my grandparents in the morning.
error: Second day.
correction: On the second day,
error_type: Preposition Error
error_severity: 3
error_description: ① Preposition Error: In English, time adverbials need to be connected with prepositions. As a time adverbial, 〈the second day〉 lacks the preposition 'On'. 'On' should be added, changing it to 『On the second day』, to make the expression conform to the norm for English time adverbials; ② Determiner Error: In English, ordinal numbers must be preceded by the definite article 〈the〉. In the original phrase 〈Second day〉, the ordinal number 〈second〉 lacks the definite article 〈the〉. It should be changed to 『the second day』; ③ Punctuation Error: According to English writing conventions, a comma is needed to separate a time adverbial from the main clause, so a comma should be added after the time adverbial.
error_sentence: I think have a good time.
correct_sentence: I think I will have a good time.
correction: I will
error_type: Pronoun Error
error_severity: 3
error_description: ① Pronoun Error: According to English grammar rules, an object clause needs a clear subject to indicate the agent of the action. The original phrase 〈have a good time〉 lacks a subject pronoun, which is a pronoun error; 『I』 should be added; ② Auxiliary Error: According to English grammar rules, the auxiliary verb 『will』 is needed to express a future action. The original phrase 〈have a good time〉 lacks an auxiliary verb; 『will』 should be added.