Crossing+the+River

There are 2 adults and 4 children attempting to cross a river using a boat. The rules of the boat are as follows:
 * The boat must carry //**at least**// one person at a time
 * The **//maximum//** load of the boat is **1 Adult** or **2 Children**
 * One child may be in the boat by him/herself
 * The boat may not travel by itself
 * No one may swim in the river

Determine the **//least//** possible number of trips needed to get all people across the river in the boat.

Solution #1

Solution #2

Solution #3