I was excited to check this book out of the library for my 9.5 year old son. He is in 4th grade and is in accelerated math and doing well. That being said, he does not, by any means love math (as I do). I am always looking for creative ways to get him to appreciate the beauty of math, to have fun with it, to see the puzzles and logic inherent in it. We loved "Games for Math" by Peggy Kaye when he was a little younger, the Code Breakers books (essentially algebra) by Mindware, the Perplexors by Mindware, etc. So I had high hopes for this. I thumbed through it, reading several of the mysteries to see if it would be something I could give him to do on his own or something that I should work through with him and was disappointed to see that it seemed much too advanced for him. He is only 3 months shy of the recommended age range, has a math loving mom who engages him in math activities at home, and is in accelerated math at school, but I didn't feel like he'd be able to do much of it completely on his own. I was hoping for problems he could solve using mental math - envisioning the way the numbers work in his head, understanding number properties, using logic and reasoning. Instead, the first puzzle requires him to calculate miles per hour using mile markers 148 and 64 and the times 12:13pm and 1:33pm. While I can work that out in my head, I'm sure he'd have to write it out to get the miles of 84 and the time 80 minutes and then he'd probably do the actual long division which he wouldn't actually NEED to do to be able to answer the question: were they speeding if the speed limit was 55 mph ? So I know that I will do it with him, so I can show him the simplicity in reasoning it out at that stage (How many miles could you go in 80 minutes if you're going 60 miles per hour ? (80) Okay so if they went 84 instead of 80, does that mean they're going faster than 60 or slower than 60 ? (faster). So, if the speed limit were 55, were they speeding )? The second one requires the child to think through probability. The third requires them to figure out least common multiples to be able to do a recipe that calls for 2/3 a cup when you only have a 3/4 cup measuring cup. I think this book might be perfect for him to do in 5th grade (or possibly 6th), and I have high hopes for using it WITH HIM when he's ready as I think it's important to show children how to use math, how to reason with math, how to do the most efficient math possible to MAKE DECISIONS rather than just how to do tedious calculations. I'm sure some kids who are naturally quantitatively inclined are able to do this in 3rd grade as the recommended age range says (3rd to 6th), but for us, I think the upper end of that range is more accurate.