BEIJING, April 21 -- Children from both home and abroad gained knowledge about environmental protection in Shanghai Saturday by celebrating World Earth Day, which falls on Tuesday - alas, a school day.

Organized by Shanghai Zoo, the Rainbow Bridge International School and the Changning District Science and Technology Bureau, the activity had the theme "Make a Change, Keep the Balance."

About 15 booths were set up in the zoo according to countries and non-governmental organizations. Each country displayed its ways of energy saving, wildlife protection and waste recycling. Games, such as painting and making leaf boats, were organized.

Yang Fanzhou, 13, found it interesting to plant a seed and prepare gorillas' food. "I will go planting more trees with my friends," she said.

Xiong Chengpei, director of the zoo, said the facility wanted to tell people through activities that the environment can be changed for the better as long as they adjust living habits.

"We encourage people to save every drop of water, every watt of electricity, and use public transport more rather than driving cars," he said.

Started in 1970 in the United States, World Earth Day, which falls every April 22, has begun to broaden the environmental movement.