Though there is some switching of roles and attributes between the twin protagonists, and between their parents, this middle grade novel isn't really about trading places. This book is more focused on second chances.
If the last few weeks had taught Amy anything, they had taught her the importance of second chances. (pg 137)
In fact, every single family member - mother, father, brother, sister, even their old dog - gets a second chance. All the major characters recreate their roles and re-invent their personalities. (Bravo to the author for including the parents too!) These transformations make the characters dynamic and the story layered.
The main issue of the book is that some of these changes occur a bit too abruptly. This is particularly true in the case of the father - for many months he can't even boil water, then he finally manages to pull together a 30-minute meal from a recipe, and a few weeks later he's considering becoming a caterer. Even for lower middle grade, this is a very short novel of only 138 pages; I'm not sure why the author didn't slow down the pace a bit and expand more on all the interesting changes taking place in these characters' lives.
Despite that flaw, I really enjoyed the time I spent with this contemporary family while they deal with very realistic situations. And Isaiah really captured my heart. The third-person narration alternates fairly seamlessly between the brother and the sister. Finally, the Mini-Society school project enhances the plot and mirrors real life.