Grade level: 4 – 5th

Skills:  Subtraction (4 digits)

Related environmental issues:  Environmental Events

Area level: Global

Earth Day is celebrated on April 22 every year to raise awareness about environmental issues and demonstrate support for environmental protection. Earth Day is one of the largest holiday in the world and is celebrated by more than a billion people each year.

1.  Earth Day  was born in the United States and was first celebrated in 1970. Maya was born in 2005. How many later was Maya born since the Earth Day was first celebrated?
2. Earth Day started being celebrated around world in 1990. How many years did it take for Earth Day to become an international event?
3. Earth Day is observed in 174 countries each year. There are 196 countries in the world.  To celebrate Earth Day in the entire world, how many countries need to be invited to celebrate Earth Day?

Source:  History

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Answer keys

1. 35 years (2005-1970=35)
2. 20 years (1990-1970=20)
3. 22 countries (196-174=22)