Viking longship (10th century)

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

Saturn

Saturn is the second largest planet in the Solar System, easily recognisable by its rings.

B-17 Flying Fortress (USA, 1938)

The ´Flying Fortress´ was developed for the United States Army Air Force by Boeing

Addition

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

Producing ammonia from nitrogen gas and hydrogen gas

Large-scale ammonia production requires high temperature and pressure and the presence of iron as a catalyst.

Quinquereme (3rd century B.C.)

The warship having several rows of oars was the typical warship of the Hellenistic era.

Archeological excavation (pit house)

Large construction sites provide archeologists searching for artifacts with a great deal of work.

Cuboid

A cuboid is a polyhedron with six rectangular faces.

Measuring time

The first calendars and time-measuring instruments were already used by ancient Eastern civilizations.

Reaction of ammonia with hydrogen chloride

Ammonium chloride is the result of the reaction of ammonia and hydrogen chloride

Reaction of zinc with hydrochloric acid

The dissolution of zinc in hydrochloric acid produces hydrogen gas.

Soldiers of the American Civil War

The American Civil War was fought between the Confederacy and the Union.

Diversity of light-detecting organs

Several analogous types of eyes have developed independently through convergent evolution.

Dissolution of hydrogen chloride (HCl) in water

The solution of hydrogen chloride in water is called hydrochloric acid.

Blitzkrieg strategy (1939-1940)

This effective strategy was based on the fast and synchronized attack of different branches of the army.

Phonograph and gramophone

Edison´s invention records and plays sound from a cylinder, while Berliner´s apparatus uses a disc.

Robots

An entertaining game about different views of spatial objects.

Cube of cubes

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

SM U-35 submarine (Germany, 1912)

Submarines had an important role in naval warfare as early as World War I.

Alkaline batteries

In alkaline batteries electric current is generated by electrochemical reactions

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