1. I want to do volunteer work at a nursing home.

2. I want to do volunteer work in a nursing home.

(Which preposition should we use? Are both OK?)

3. I want to do volunteer work at an orphanage because I want to take care of orphans who are helpless.

4. I want to do volunteer work at a nursing home because I want to take care of elderly people. I want to be of help to them.

5. I want to do volunteer work at a nursery school because I am interested in caring for little children. I want to play with them.

(Would you check the three passages? Correct errors, please.)

All five sentences are very good. Nice!

1. Both prepositions "at" and "in" can be used in this context, but they convey slightly different meanings. "At" suggests volunteering in a specific location within the nursing home, such as a common area or a specific department, whereas "in" suggests being involved and engaged in the overall activities and operations of the nursing home. Therefore, you can choose either preposition based on the level of involvement you desire.

2. The sentence is correct grammatically and conveys your intention to volunteer in a nursing home.

3. The sentence is correct. However, it may be more sensitive and respectful to refer to the children as "children" rather than "orphans." Using the term "children" recognizes their identity beyond their orphan status.

4. The sentence is correct and effectively expresses your motivation to provide care and assistance to elderly individuals in a nursing home.

5. The sentence is correct. However, instead of saying "I want to play with them," you may want to consider rephrasing it to say "I want to engage and interact with them" to highlight the educational and developmental aspect of working with young children.