[header] How to calculate modulus [title] Note that material stress is caused by axial stretching force. [step] For example, pulling straight out on a piece of taffy will stretch the taffy due to applied stress. [title] Understand that material strain is caused by shearing force perpendicular to the axis of the material. 
[step] For example, pushing on the middle of a tennis racket string will bend the string due to applied strain. [title] Measure the proportional fractional volume change (also known as dilation) of the material.