Cell size and scale
Just a neat link my hubby found this morning... http://learn.genetics.utah.edu/content/begin/cells/scale/ You can zoom in to see these various things starting from a coffee bean and down to a skin cell, human egg, red blood cell, bacteria, viruses, hemoglobin, glucose and molecules, etc., all the way "down" to a carbon atom. In measuring scale, you go from millimeters (0.001 or 10 -3 m) to micrometers (0.000001 or 10 -6 m) to nanometers (0.000000001 or 10 -9 m) to picometers (0.000000000001 or 10 -12 m).