Place a teaspoon of salt in each of the two hollows. Observe at the end of the laboratory session. The next day, observe the potatoes again and explain any differences between the two. Don't leave any skin on the surface. Place them in a jar of water that contains several drops of dark food coloring.
Food needs to diffuse into the cell and waste material needs to diffuse out of a cell.
Place an egg in a pint jar and fill the jar with water. Observe every two or three days for two weeks. Make sure the egg is always submerged in water. Tap the rounded end of a second egg with a spoon so that it has a small crack. Remove a few pieces of the shell so that there is a hole the size of a dime or smaller.