The Dragonvale Middle School chess team consists of two boys and three girls. A photographer wants to take a picture of the team to appear in the local newspaper. She decides to have them sit in a row with a boy at each end and the three girls in the middle. How many such arrangements are possible? 
Overseas Competition->Knowledge Point->Counting Modules->Permutations and Combinations->Combinations
Boy, Girl, Girl, Girl, Boy.There are $$2\times 1=2$$ ways of arranging two boys; there are $$3\times 2\times 1=6\textasciitilde$$ways of arranging $3$ girls. Therefore, there are $$2\times 6=12$$ ways of arranging all students. 