The microworld, as we defined it, goes from 1 to 1000 microns. We know that paper is about 100 microns. What about stuff smaller than that?
Below is a scale drawing. Your job is to eyeball the sizes of the different things in this world using the drag-and-drop microscope viewing area. Fill in the table, then click check to see how close you were.
So once again, the microworld is basically the world of cell-sized things, from giants like multicellular animals (dustmites), to big single-celled organisms (like protists, euglena and paramecium), down to plant and animal cells (generally in the 5 to 30 µm range). Some of the largest structures inside cells, like the nucleus, mitochondria, and chloroplasts are just at the bottom of the microworld.