Estimation of the didactic complexity of natural scientific concepts

The didactic complexity of the natural science concept named the characteristic proportional to the amount of time or effort required to the pupil of the 5th class for it studying. For an estimation of the didactic complexity of 42 chemical, physical, biological and geographical concepts experts in pairs compared objects and placed cards with their names on the difficulty scale. The analysis of the received results and the calculation of terms number in definition of concepts allow to say that the concept “DNA” is about 8-12 times more difficult than the concept “water” and about 1,5-2,5 times more difficult than the concepts “galaxy” and “black hole”. The uniform criteria which allowing to divide all scientific terms depending on the level of abstractness into 5-6 categories are offered; classification more than 120 concepts are considered. The received results can be used for the complexity estimation of textbooks on natural science disciplines.