This essay starts by laying out the topic of what is computer science, and
then talks about the definition of science, followed by the definition of 
computer, and then a proposed CS definition. 
To make it more structured, add a sentence about "We will
first discuss definitions for science and then for computers" to the
first paragraph. 

Also, the last two paragraphs on related disciplines seem out of place
when reading the essay straight through. To clue the reader in, set
the scope of the essay to include "topics related to CS" at the very
beginning. This could be done by adding "And what scientific fields
are related to computer science?" to the first paragraph. 
 
Paragraphs were well-written in general.