How to define the derivative of a function at a point x=a.
Understanding the acceleration of an object.
How matter changes phase from liquid to gas.
How matter changes phase from liquid to solid.
Understanding the behavior of an object in free fall.
How to estimate a limit using a table of values.
How to understand the idea of slope.
Understanding the process of evaporation.
Understanding the process of condensation.
How to find the speed of transit when the time of two different legs is known.