BACKGROUND:

Cells are the fundamental units of living material. The bodies of all living things are formed from cells, and without cells there would be no life. Every large living thing is made of billions of cells.

A cell contains special structures called organelles which have specific functions for maintaining the health of the cell. These functions include taking in food and breaking it apart into simple molecules, releasing energy from food, building and repairing cell parts, getting rid of harmful wastes, and making more cells.

There are thousands of different kinds of living things that are made up of only single cells. They are restrictive in what they can do, however, because one cell just can't conquer the world.

In most plants and animals, the cells are organized to do different types of jobs. In plants, for instance, there are specialized root cells whose function is to take in minerals and water. These specialized cells are arranged into tissues that do the same job. Muscle tissue, for example, is made up of many individual muscle cells. Different tissues that work together form organs. Examples of organs include the stomach, kidneys, and lungs. Organs are groups of tissues that work together to perform a specific function. Organs do not operate in isolation and together they form systems, like the respiratory, circulatory, and digestive systems.

PROCEDURE:

1. Discuss the main organelles of a cell. Emphasize the importance of the nucleus and its function. Explain the differences between plant and animal cells, especially the presence of chloroplasts and a rigid cell wall in plant cells.
     
2.  Have the students construct a paper model of a plant cell and an animal cell by cutting and pasting from the provided sheet. The major part is that the animal cell will not have a cell wall and chloroplast.