One reason to read multiple books on the same topic is to build your child’s vocabulary. To learn new vocabulary words, children need repeated exposures to the word in meaningful contexts. This is one reason why reading the same book over and over is so valuable, but encountering the word in new books is also important. Talking about similarities and differences between books on a similar topic offers a rich opportunity for children to think about and use new words.
Tumble Books | Homework Help
Center for Early Literacy Learning
Too Small to Fail
Reading is Fundamental
Helping Children Read and Succeed
Ohio Department of Education
PBS Kids | Sprout