Sam picked up the long stone and held it out to Willie. “So, what was it Ms. Jones said about dinosaur bones in class the other day?”
Willie took the stone and examined it. “Well, she said…”
This is known as the “As you know, Bob” dialogue faux pas. This happens when a character is being told something they already know just so the author can get the information to the reader or remind them of something. This doesn’t happen in real life, and it shouldn’t happen in your fiction. Find another way to get the information across.
When a person starts recounting a lecture or a conversation I was involved in, my response is usually, “Yeah, I was there. Remember?”
If the information is that important, have it delivered to someone who doesn’t already know. And, if it’s really, really important, show us the scene where they found it out. If there’s a quick lesson about dinosaur bones at the beginning of the book, I’m going to assume it’s important and won’t need a refresher when a bone is thrown into the plot. Quite the opposite, I will have been waiting for it.
Things like this weigh your story down and insult your reader’s intelligence.