Enjoy the adventures of Henry, Jessie, Violet, and Benny Alden—The Boxcar Children. Gertrude Chandler Warner wrote the first 19 stories, but there are now 140 titles in The Boxcar Children Mysteries series.
The Boxcar Children tells the story of four orphaned children, Henry, Jessie, Violet, and Benny. They create a home for themselves in an abandoned boxcar in the forest. They eventually meet their grandfather, who is a wealthy and kind man (although the children had believed him to be cruel). The children decide to live with the grandfather, who moves the beloved boxcar to his backyard so the children can use it as a playhouse.
Additional resources and how to use these books in the classroom can be found here: https://www.boxcarchildren.com/in-the-classroom/