Endangered coral reef in Australia

Grade level:  5th – 6th grades

Skills: Measurement (unit conversion) 

Related environmental issues: Biodiversity

The Great Barrier Reef in Australia–the  biggest coral reef system in the world– is home to about 400 types of coral and 1,500 fish species.  However, the corals there have been killed by overheated seawater resulting from recent climate change. Terry P. Hughes, a researcher of coral reef, reported that 67 percent of the corals had died in the north of the Great Barrier Reef.


healthy coral (National Geographic)


dying (left) and dead (right) coral    (abc.net.au)

Convert into given unit of measurement.

  1. The Great Barrier Reef stretches more than 1,600 miles.  1,600 miles = ________ km
  2. The Great Barrier Reef stretches more than 1,600 miles.  1,600 miles = ________ feet
  3. About 13,000 years ago, the sea level of Australia was 200 feet lower than the current level.    200 feet = ______ inches
  4. The observations suggested that 20% of coral in the central area of the 344,000 sq km reef is dead.     344,000 sq km = _______ sq miles

1 mile =  1.61 km

1 mile = 5,280 feet

1 foot = 12 inches

1 sq km = 0.39 sq miles


Sources: NY Times, March 15, 2017, Life Science & News.com.au


Answer keys

  1. 1,600 x 1.61 = 2,576  (km)
  2. 1,600 x 5,280 = 8,448,000 (feet)
  3. 200 x 12 =2,400 (inches)
  4. 344,000 x 0.39 = 134,160 (sq miles)

Loss of salmon because of dams

Grade level: 3rd – 5th grades

Skills: Measurement (Length: inches and feet)

Related environmental issues: Biodiversity & Water

People have constructed many large dams for the purpose of flood control, water supply, and electricity generation. However, dams can have negative environmental impacts by changing the environment, affecting natural habitats in the dam areas. For example, the Elwha River in the Pacific Northwest of the United States lost nearly all of its salmon due to the construction of the two dams. A 108-foot dam and a 210-foot dam blocked their path to the freshwater stream of their origin to lay their eggs.  The dams were removed in 2014 to restore the destroyed ecosystem, and salmon began to make a return to the river after the removal.


  1. What was the hight difference between the two dams?
  2. How high were the two dams in yards?
  3. Height of the Statue of Liberty from her heel to the top of her head is 1,338 inches. Is it taller than the 108-foot dam or shorter?

Source: WWF, 2016. Living Planet Report 2016


Answer keys

1. 102 foot  (210 – 108 = 102)

2. 36 yards and 70 yards

3. The statue of Liberty is taller than the 108-foot dam by 42 inches.

108 x 12 = 1,296 inches