Comparing is noticing differences and similarities of things. Do you see similarities and differences in these two leaves?  How are the two leaves the same?  How are they different?

Almost everyone compares every day.  You compare prices at the store so you can get the most for your money.  You compare all the pieces of cake in order to select the biggest one! 

Scientists compare a lot.  A seasons scientist might compare the shapes of the leaves on a tree to leaf shapes in a book to determine what species of tree she is studying.  In the fall she might compare the colors of the leaves to each other and to a color chart to learn how the tree reacts to seasonal changes. 

Look at the two leaves on this page.  How are they alike? How are they different?  Woohoo! You are comparing!