The inability to differentiate certain shades of colour is called colour vision deficiency.
A rock relief located in Northeast Bulgaria, probably carved at the end of the 7th century.
The architecture of traditional Samoan family settlements reflect the unique culture of their inhabitants.
Modern Slavs live in 14 European countries that can be classified into 3 groups.
Oil tankers appeared in the late 19th century; today they are among the largest ships.
The Northern white-breasted hedgehog rolls into a ball to protect itself.
There are two basic cell types: prokaryotic and eukaryotic cells.
The mosque, built in a distinctive architectural style, is the largest adobe structure in the world.
This 3D scene explains the correlation between the ratio of similarity and the ratio of volume of geometric solids.
Cossacks, members of independent semi-military communities, played an important role in the history of Ukraine.
A presentation of the major administrative units of China.
Practise the German alphabet and form words from the letters.
Practise the English alphabet, build words from letters.
Practise the Russian alphabet, build words from letters.
The adrenal glands are responsible for maintaining homeostasis and producing a rapid response in stressful situations.
There are various types of instruments used for measuring temperature.
This scene explains the structure and functions of the bones.
By positron emission tomography (PET), we can obtain visual information on our internal organs without making any surgical incisions.
The range of applications of unmanned aerial vehicles ('drones') keeps growing.
The vacuum cleaner creates a partial vacuum and sucks up dust with the help of the incoming high-pressure air.