During a recent visit with my 12-year old daughter’s science teacher, I mentioned that I had read a few books on cell biology over the past couple of years and that I was interested in sitting in on one of the upcoming sixth grade science classes--my daughter had mentioned that they were beginning to study cell biology. I mentioned a few of the things that I had found interesting about cells to the science teacher. After noticing my enthusiasm, she retracted her invitation to watch the class and, instead, invited me to teach part of the class. A few days later I made my science teaching debut. I advised the sixth-graders that although I work as a lawyer during the day, I often read science books, and I often write about science on my website. I told them that I had no serious science education at the Catholic grade school I attended. I didn’t have any biology class at all until I was a sophomore in high school. That was mostly a nuts and bolts class taught by a Catholic nun who failed show the excitement the subject deserved. She also forgot to teach by Theodosius Dobzhansky’s maxim that "nothing in biology makes sense except in the light of evolution." I told “my” class that anyone who studies cells with any care will be greatly rewarded. Studying cells is actually autobiographical because “you are made of 60 trillion of cells.” These cells are so small that people cannot even see them. One of the students then confused trillions for millions. “Keep in mind,” I cautioned, “that a trillion is a million million.” With regard to their size, there is only one human cell--the human ovum--that you can see with the naked eye—it is much bigger than the other cells in your body. Despite its tiny size, the human ovum is so incredibly small that it’s smaller than the period at the end of this sentence. See this wonderful illustration of the size of human cells, and many other small objects.

The volume of a eukaryotic cell is typically 1000 times larger than that of a prokaryotic one. Page 28