"I used to have this stack of hard-copy journals on my desk waiting to be read," said Catherine Poling, an assistant principal at Kemptown Elementary School, also in Frederick County, Md., who ran a blog last year when she taught third grade at a nearby school. "Now I can react to what they say immediately, and students can respond to each other."

In one blog entry, for instance, Ms. Poling asked her students what qualities they looked for when rating books for a statewide award. When several students responded that a book has to be creative and grab their attention, she posted a follow-up question asking them if they used the same criteria for both fiction and nonfiction books.