Endocrine system

Glands of the endocrine system secrete hormones into the blood.

Two-stroke engine

A two-stroke engine is a type of internal combustion engine with a cycle of only two (power) strokes.


The most ancient group of animals, they live underwater, lack real tissues and body symmetry.

Amoeba proteus

Widespread heterotrophic unicellular organisms with constantly changing shapes


One of the most important monocot crops.

Edible frog

This animation demonstrates the anatomy of amphibians through the example of a common species of frogs.

Fat molecule

Three saturated fatty acid molecules linked to a glycerol molecule.

Horse chestnut

This animation demonstrates how horse chestnut trees change throughout the seasons

Oil molecule

Triglycerides containing unsaturated fatty acids are liquid at room temperature.

Secondary structure of proteins

Polypeptide chains are composed of amino acids and can appear in alpha-helix or beta-sheet form.

Types of bridges

Types of bridges include beam-, arch-, suspension-, cantilever and truss bridges.

Types of gears

Two meshing gears transmit torque during their rotational motion.


This animation shows optical and radiotelescopes used in astronomical observation.

Battle of Issus (333 BC)

The battle ended with the overwhelming victory of the Macedonian army over the Persian army led by Darius III.

Common earthworm

The anatomy of annelids is demonstrated through the example of the common earthworm.

Medieval Chinese Emperor

The Emperor of the vast Far-Eastern empire was the lord of life and death.


Observatories are often built at high elevations to minimise the effects of atmospheric turbulence

The evolution of data storage

The capacity of data storage devices have increased at an incredible rate during the past decades.

Optical instruments

A wide variety of optical instruments are in use today, ranging from microscopes to telescopes.

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