One job of a writer is to relate information to the reader as seamlessly as possible. (Good ole "show, don't tell.")
But that is sometimes tricky and takes a lot more effort than a non-writer might realize.
Making that skill all the more difficult is the fact that you, the writer, know information that the reader does not - so it's sometimes hard to gauge what to leave to the reader to find out as she reads along vs. what to go ahead and give her right away.
One of the most valuable "tools" for a writer is a pair (or two) of fresh eyes, i.e., a cold reader.
A cold reader can tell you what she doesn't understand, what she needs to know sooner, etc.
Let me give you two examples from personal experience:
I recently had a teacher relate to me that her students liked the way I didn't tell them who Ugly was in the opening scene of Greetings from Nowhere - that they had to read another paragraph or two to find out.
"Harold would have known what to do," Aggie said to Ugly. She tossed the unopened envelope into the junk drawer on top of the batteries and rubber bands, old keys and more unopened envelopes. "Let's go sit and ponder" Aggie said.
So, the reader doesn't know who Ugly is.
If I had gone on much longer, however, young readers would probably have gotten frustrated. I needed to get the information in there soon - but as seamlessly as possible.
She scooped up the little black cat and shuffled across the dirty orange carpet.
There - now we know.
I kept the reader waiting just long enough to make them curious - but not frustrated.
But in my current work-in-progress, I wasn't as successful:
When the BB hit Henry square in the eye, she had screamed bloody murder and carried on so much that when Velma came running out of the house to see what all the fuss was about, she had thought it was Charlene who’d been shot in the eye.
It wasn't until another page and a half that I identified Velma as his grandmother.
Initially, it just felt too telling to insert "his grandmother" in front of Velma.
I knew who Velma was - so it was hard for me to gauge whether or not the reader really needed to know this right away.
Apparently the reader did need to know.
Two topnotch editors - reading with fresh eyes - wrote "Who is Velma?" in the margin.
I'll be honest with you - I didn't really want to insert "his grandmother" - and it felt not-very-seamless to me - but I knew I had to do it.
Sometimes, you just have to listen.
I heard an agent speak at a conference years ago and I will never forget her "formula" for a good children's book: Make 'em laugh; make 'em cry; and make 'em wait.
I realize the "make 'em wait" part applies primarily to plot - but I also think it should apply to "smaller" elements of the story, as well.
But this can be one of the trickier elements of writing for children - how long to make 'em wait for information.
I think the answer comes from a combination of instinct, experience, and the value of cold readers.
(I realize that I've imparted zero information in this supposed "tip" - but sometimes food for thought is as good as a tip. At least, that's my story and I'm stickin' to it.)