Disclosure: I received complimentary products to facilitate this post. All opinions are my own.
The Science Museum of Minnesota currently has an exhibit about how kids develop. It's been fun to see my girls interact with things on the exhibit as we've visited over the years, to see how their understanding changes and matches the developmental stages described in the exhibit. As someone who studied basic psychology and cognitive development while getting my teaching degree, it's also been fun to see that development in my own children. Having an understanding of developmental milestones really does help when parenting, to make age-appropriate decisions and understand behavior - both good and bad.
That's the idea behind Think Like a Baby: 33 Simple Research Experiments You Can Do at Home to Better Understand Your Child's Developing Mind. Amber Ankowski, PhD, and her husband Andy Ankowski (co-founders of the blog The Doctor and the Dad) write a series of things to do at home to re-create some classic child development experiments. Being able to see things in person is so much more helpful than reading about them, and they make it easy to do so, using common household objects to understand how your kid is thinking.
But they go beyond the theoretical and into the practical. After each experiment, they relate the real-life implications of the experiment, with tips on appropriate toys, how to appeal to kid logic, and more. The book is easy to read, with clear explanations that can be easily understood by anyone, with or without any knowledge of child psychology. The experiments are fun, and actually apply up into early childhood, so I was able to do some with my own kids at age five and seven. They enjoyed it as much as I did, and it's always nice to see what your kids can't express themselves.