Rotating a rectangle around its axes of symmetry or around its sides results in solids of revolution.
Viruses consist of protein and DNA or RNA; they reprogram infected cells to produce more viruses.
A colourless, odourless gas, an important component of the atmosphere, indispensable to sustain terrestrial life.
The prosperity of the eastern part of the Roman Empire started in the early 4th century, during the reign of Emperor Constantine.
Flat feet, or fallen arches, may cause a number of health problems.
Hovercraft are capable of travelling at high speed above the surface of water.
During World War I France was part of the military alliance called 'Triple Entente'.
Inhabitants of ancient Egypt wore characteristic clothes and jewellery.
This animation demonstrates the development of freight transport, from horse-drawn carts to modern lorries.
King Darius as well as Xerxes built pontoon bridges across the Bosphorus for the Persian army.
The Soviet-made satellite was the first spacecraft to be launched into outer space (in October 1957).
Influenced by Western Europe, the Tsar attempted to modernise the Russian Empire.
Ancient Indian war elephants were used as ´tanks´ in battles.
The medieval Arab inventor, Hassan Al Rammah designed the world's first operating torpedo.
A prehistoric amphibian and an early representative of the Tetrapods, which became extinct 360 million years ago.
A floatplane (sometimes called hydroplane) is an aircraft capable of taking off not only dry land, but water too.
This animation presents the current refugee crisis from various points of view.
The battle, that is considered to be a tactical masterpiece, meant a decisive victory for Alexander the Great against Persia.
One of the most important parts of a medieval castle was the Knights´ hall.
Calculating the volume of a sphere is possible using an appropriate cylinder and cone.