This animation demonstrates the main sources of air pollution: agriculture, industry and urban settlements.
Airports provide infrastructure and services necessary for aviation.
Ports must provide necessary infrastructure and services for industry and marine transport.
An ant colony consist of a queen, male ants and workers.
This animation demonstrates the structure and most important peripherals of desktop computers.
A wide variety of optical instruments are in use today, ranging from microscopes to telescopes.
The battle ended with the overwhelming victory of the Macedonian army over the Persian army led by Darius III.
The Emperor of the vast Far-Eastern empire was the lord of life and death.
The pericarp of real fruits develops from the carpel, while the pericarp of pseudofruits develops from other parts of flowers.
A species of mollusc widespread in freshwaters.
Moles are small subterranean mammals with modified, spade-like forelegs.
Division of space by three intersecting planes in several different arrangements.
The United States entered World War II after the devastating attack by the Japanese navy.
To calculate the volume of a tetrahedron we start by calculating the volume of a prism.
Synovial joints can be categorised by the direction of movement they allow.
A hot air balloon is a balloon aircraft which is lifted by hot air.
Regular dice can be used for solving statistical and probability exercises.
The Crow are Native Americans who inhabited the Yellowstone River valley.
A periodic climate pattern that occurs across the tropical Pacific Ocean every five years.
Cold and warm fronts are formed where bodies of cold and warm air meet.