The point to reading is comprehension, but most children don't truly understand these harder books at the level they are meant to be understood. It is important for children to "think" while they read and move beyond getting the "gist" of it. Starting this transition with a reader feels a lot like throwing on the breaks so to speak. We need to practice thinking deeply with a 2nd or 3rd grade book before trying to read a 4th or 5th grade book. Books written for higher grades often contain content that is beyond the developmental level of a 2nd grader. The characters are older and are thinking and acting differently than them. Historical content and information from higher grades often makes it difficult for younger readers to understand what is happening in context.
Readers who reach this level in 2nd grade are just begining their journey as a reader who can think deeply, ask thoughtful questions, and discuss what they've read in a meaningful way with other readers. I try to guide these students in a discussion about what they've read rather than having them just retell what they've read. I often begin by asking them what they were thinking or wondering while they read. Below you can listen to the discussion that a reading group is having about a chapter they read.