Show the children an actual microscope or a picture of a microscope. A scientist named Anton von Leeuwenhoek developed the microscope. He was a cloth merchant and made his first microscope to help him inspect the cloth he was buying and selling. He also became interested in the way food moved within the body and eventually became the first person to correctly describe red blood cells. Explain to the children that their bodies are made of millions of cells.
Cells come in all different shapes and sizes.
Cells from one part of your body may look very different than cells from another part of your body because different cells perform different jobs. Even after you stop growing your body continues to make or produce cells to replace cells that wear out and die. For instance on the outside of the body, skin peels or flakes off when it gets dry because of the weather or the sun. On the inside of the body, cells in your intestines wear away as food is digested and passes through your body, so your body makes new cells to replace the ones that are lost. Tell the children that cells are joined together to make body tissues, body tissues make up organs, and organ works in systems.