Grades Kindergarten through 4th are in what is known as the Grammar Stage. It is a time period when kids naturally acquire and remember knowledge, facts, and information. Grammar is the foundation of all learning; it's the building block of all types of written and verbal expression.
We often tell parents considering a classical education to think of their young child’s brain as a filing system. The child memorizes facts (history, math, grammar, Latin, science, etc.) and “files” them away to retrieve at a later date. While a first grader may not understand the Pythagorean Theorem, they will be able to retrieve the definition of the theorem when they are older and need to apply it to solving a math problem.