Addition

Addition is a reaction in which the molecules of two or more substances unite without the formation of a by-product.

Cuboid

A cuboid is a polyhedron with six rectangular faces.

Cube of cubes

An exercise about the regular hexahedron built from unit cubes to help deepen your knowledge of cubes.

Robots

An entertaining game about different views of spatial objects.

Mercury

Mercury is innermost and smallest planet of the Solar System.

Neptune

Neptune is the outermost planet of the Solar System, the smallest of the giant planets

Venice in the Middle Ages

Medieval Venice owed its wealth to its flourishing maritime trade.

Cannon operation (18th century)

The cannon was an important type of firearms at the beginning of modern history, widespread both on land and water.

Viking longship (10th century)

These excellent shipbuilders and sailors travelled great distances on the seas and rivers.

Medieval smithy

The work of smiths – one of the first professions in history – became even more important in the Middle Ages.

Farming techniques

Farming techniques evolved with the development of human civilisation in the Middle Ages and the Modern Age.

Golden Gate Bridge (San Francisco, 1937)

The suspension bridge that stretches above the strait between San Francisco Bay and the Pacific Ocean was opened in 1937.

Olympia (5th century BC)

The Olympic Games, held in the town every 4th year after 776 BC made it one of the centres of ancient Greece.

Medieval dungeon

A wide variety of torture devices were in use in medieval dungeons.

Working-class district (19th century)

Typical working-class districts with unhealthy living conditions were built at the time of the Industrial Revolution.

Chlorination of methane by a substitution reaction

During the substitution reaction the hydrogen atoms of methane are substituted with chlorine atoms, the by-product is hydrogen chloride.

Calcium carbonate (CaCO₃)

Limestone is a widely and diversely used material.

Tanning, skin cancer

The topmost layer of our skin is the epidermis, which contains melanocytes.

Soap

Fatty acid molecules consist of a polar head and a non-polar tail, therefore they are suitable for removing fat stains.

Formation of hydrogen molecules

Hydrogen atoms within hydrogen molecules are held together by a covalent bond.

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