In 1st grade I could not see how a dime could possibly be worth more than a nickel. The nickel was bigger, after all; it should obviously be worth more.
By 5th grade I realized the dime was more valuable because it was made of a more valuable metal. So even though it was smaller, its total worth was greater than the nickel.
It took until high school to figure out that both the dime and nickel are made of completely worthless metals. The dime is worth more because the US Treasury says it is worth more.