The Clever Farmer

A farmer stood at a riverbank with a goat, a bundle of grass, and a lion. He wanted to cross the river, but his boat could contain only one animal or item, excluding the farmer. If he took the lion first, the goat would eat the grass. If he took the grass first, the lion would eat the goat.

Finally, he hit upon an idea. He took the goat, crossed the river on the boat, and left it at the second bank. Then he returned and took the lion (or the grass) with him. 

He left the lion (or the grass) at the second bank but took the goat on his return trip. He left the goat at the first riverbank and brought the grass (or the lion) with him. 

He left the grass (or the lion) at the second riverbank with the lion (or the grass) and returned to the first riverbank. Then, he took the goat with him and made his final trip to the second riverbank.

Thus, with his animals and the bundle of grass, the farmer crossed the river without any problems.