I looked into Glenn Doman's books a little further and discovered a book about teaching math to very young babies. As a math dork, I had to check it out.
The book recommends using "dot cards" for teaching numbers to babies. It turns out that infants can look at the dots and recognize the quantity. They can identify very large numbers without knowing how to count and without knowing any numerals.
It made a lot of sense to me that these cards are a better way to introduce an equation than writing 4 + 5 = 9. The symbols that we use to represent mathematics can be abstract. We have assigned numerals to the quantities, but they are not necessarily intuitive to children. A child or baby can understand addition better visually (by seeing the dots).
I realized that we already know that this is true for many older students as well. In Algebra, we also assign symbols to quantities. I decided to try to adapt the dot cards to a similar style of visual learning cards that could be used for representing algebraic expressions.
Laws of Exponents
The Distributive Property
combining like terms
Here's the affiliate link to the book I read. Check it out if you have little ones and a math mind!