What comes to mind when you think of matter give an example

Question

"Is Light Matter?" After reviewing this webpage: https://www.nap.edu/jhp/oneuniverse/matter_64-65.html#section - Please respond in two paragraphs with:

1. In the last two weeks we have investigated time, length, and mass at very high velocities. What unifying physical principle ties all three of these investigations together? 
2. What comes to mind when you think of matter? Give an example of something acting like a particle, provide a second example of something acting like a wave, and explain how light fits into this picture.