Reddit reviews Mouse Tales (I Can Read Level 2)

9 year old girls

They're old enough to be reading chapter books, but you didn't mention how advanced they were...

Hmm...this might be tricky...

If they like animals:

Summer of the Wolves

A recently orphaned twelve-year-old girl and her younger brother leave a foster home in California to stay with their estranged uncle, a biologist studying a wolf pack in the woods of Minnesota. Heartfelt and informative.

If they like fantasy:

Fablehaven

Kendra and Seth's grandfather has a secret. His woods is a sanctuary for all creatures magical and mystic.

If they like mysteries:

Frightmares: Cat Burglar On the Prowl

Peg Kehret has written a score of mysteries, but the best for middle readers are the Frightmares. Kayo and Rosie run into quite a few mysteries, and quite a bit of danger.

If they want to read about normal kids:

You can't go wrong with Beverly Cleary; I will never not recommend her. If I had to choose a single book of hers to recommend...

Dear Mr. Henshaw

7 year old boy

If he likes fairy tales:

The Stinky Cheese Man & Other Fairly Stupid Tales

The best set of fractured fairy tales I can think of. And perfect for a seven year old boy.

If he likes mysteries:

Jigsaw Jones

Encyclopedia Brown and its emphasis on logic and catching people in lies might be a touch too much for him at the moment, so I'm going to recommend Jigsaw Jones, the other elementary sleuth solving mysteries at reasonable rates. There's approximately a bazillion Jigsaw Jones books, so take your pick.

4 year old boy

If he likes little stories:

Mouse Tales

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I may need a little extra time to think of books for the other kids.