You can grow a plant from a bean quite simply, and it is a great science project for a couple of reasons. The bean is large enough to be able to see it as the plant grows, and it grows quickly so you don't have to wait for months before you can see anything tangible.
List all the different parts of the bean on the poster board. This can be done by taking digital pictures of the bean, expanding them on your computer, printing them out and gluing them to the poster. Label the different parts with lines pointing to the pictures.
Begin planting beans six weeks before the project is due. Plant a couple in a regular 8-ounce plastic disposable cup filled with potting soil. The following week, plant two more seeds in another cup. Label each cup with the date of planting. Continue this process through six cups of planted beans. By the time your project is due, you can show six different stages of growth. Each week, write down the growth progress of the beans in each cup.
Present information about the bean. Find out its nutritional value, how it is used around the world and why it is important to grow. Give information about where it is grown and the different regions it can grow in. You can list this information on your poster or present it in person to the class.
Prepare note cards for each cup, listing the information you have recorded each week. Write down the growth measurement you took each time and what changes have happened to the plants in each cup.