Whenever you have a cut or scrape on your skin, you can see the healing take place over a period of time. While the wound heals, new cells are made to replace the destroyed and damaged cells. The new cells are formed by cell division. A fourth important result of cell division is the growing process. After a cell divides, both new cells grow and divide to form more new cells.
Some cells can divide every few hours.
As the number of cells increase in an organism so does its size. Have students determine the number of cells formed from a single cell in 24 hours if division occurs every two hours. Use either planarian or tubifex worm to demonstrate regeneration. Cut each worm as shown and separate the sections into individual dishes. Add a small amount of water to each dish.