Bats are Not rodents.
More Info: Bats are mammals, and in fact, with over 1,000 bat species, bats comprise almost 25% of all mammals.
What Is a Rodent?
A rodent, from the mammal order rodentia, is the largest order comprising almost half of all mammals. Rodents are classified as having upper and lower incisors that grow continuously and must be gnawed down to shorten and maintain. Common rodents include mice, rats, chipmunks, squirrels, guinea pigs, voles, porcupines, beavers, and gerbils. The bat, as well as weasels and moles are often confused as being part of this order. 
What Is a Mammal?
A bat is a mammal because it shares the two characteristics necessary to be classified as such. Bat mothers produce milk to feed their young, and they have hair. They also possess other traits characteristic of mammals such as bearing live offspring, being warm-blooded, possessing differentiated teeth, as well as four limbs.
With over 1,000 bat species, bats comprise almost 25% of all mammals.
 “Rodents Facts, information, pictures | Encyclopedia.com articles about Rodents.” Encyclopedia.com | Free Online Encyclopedia. N.p., n.d. Web. 27 Sept. 2011. <http://www.encyclopedia.com/topic/Rodents.aspx#2-1E1:rodent-full>.
”Chiroptera.” UCMP – University of California Museum of Paleontology. N.p., n.d. Web. 27 Sept. 2011. http://www.ucmp.berkeley.edu/mammal/eutheria/chiroptera.html
 “What’s A Mammal?” Discovery Education. N.p., n.d. Web. 27 Sept. 2011. <http://www.discoveryeducation.com/teachers/free-lesson-plans/whats-a-mammal.cfm>.