1) The Earth's core is primarily composed of iron and nickel and is as hot as the surface of the sun.

2) The International Monetary Fund (IMF) and the World Bank are international financial institutions that work to promote global financial stability and economic development.

3) The first modern health insurance policy was introduced in Germany in the late 19th century.

4) A newborn kangaroo is about 1 inch (2.5 centimeters) long and weighs less than a gram.