When dealing with functions of a real variable a critical point is a point in the domain of the function where the function is either not differentiable or the derivative is equal to zero. A point is an exact location. - Numbers and counting - Shapes and measuring - Patterns and sequences - Probability and logic - Data and statistics.
When dealing with complex variables a critical point is similarly a point in the functions domain where it is either not holomorphic or the derivative is equal to zero.
The idea of point is an abstraction that distills our understanding of the concept of location. Will not only change your childs perception of numbers but give them the skills and understanding to apply the principles in their everyday life. No matter how far you zoomed in it would still have no width. - Numbers and counting - Shapes and measuring - Patterns and sequences - Probability and logic - Data and statistics.