This model represents a scale of size of different objects starting with the things surrounding us in ordinary life and ending with atoms and molecules. Interaction between the atoms and the molecules is a subject of chemistry. One can see that the size of molecules is not much smaller in compare to the size of the smallest living creatures like amoeba or infusoria. Indeed, the sizes of these creatures differ from a length of stretched molecules of DNA or the largest protein just in 1-3 orders. Therefore, in respect of the size a relation between natural living objects (starting with the largest and ending with the smallest ones) and atoms and molecules that compose these living objects may be presented as a stairs formed by different sizes of the objects. Yet it is important that the size of inorganic molecules (like molecule of water) are smaller than the smallest cells in several orders. A difference between living organisms of various sizes and the size of nucleus of atom is even much more pronounced. In this model you may initiate playing of series of images that illustrate a variability of the sizes by pressing on the "Start" button. The playing is cyclic, you may arrest it by the "Stop" button or return it into initial state by the "Reset" button. Alternatively, you may click on the scale and slider would skip to the desired place. At last you may catch the slider by mouse and drag it to see a couple of images corresponding to this sector of the size scale.