Astronomy - Spiral Arms

PLease answer the prompt correctly by creating a Powerpoint presentation. 

Lesson 15 – In Quest of the Universe Chapter 16

Galaxies

Assignment 15.2 – Conflicting Theories about Spiral Arms

Assignment Title: Conflicting Theories about Spiral Arms
Lesson 15


Directions:
Follow the instructions for the assignment and turn in your response to the instructor as directed.
Cite using MLA any online references or local sources (newspaper, online journal, reference book, etc.) you have used in your research and your response.

Assignment Instructions:
In the textbook, two analogies are provided to explain these theories: a highway for the density theory and a forest fire for the self-propagating theory.

Devise a presentation that explains and contrasts these two theories, and develop different analogies to help with the explanation.