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All plants need three things to grow; nutrients, sun and water. Hydroponics is the science of growing plants in a liquid (water) instead of a solid (soil). This science project will illustrate the benefits and limits of this method. Growing a potato in water for a science project will allow students to see the growth of a root system and experiment with how different nutrients affect the growth of the potato. This experiment will follow the scientific method of discovery from forming a hypothesis through to analyzing data.
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Forming a Hypothesis
Introduce students to the idea of growing plants in water. Remind students that all plants need sun, water and nutrients to grow. Ask the students the following questions:
What do you think will happen if a potato is grown in water?
What can be done to the water to help the potato grow?
Where should the growing potato be placed?
Will a potato grow faster in dirt?
Students should write down their predictions before beginning the experiment.
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Growing a Potato in Water Science Project Instructions
Each student or group of students should have three glass containers with wide tops, three potato pieces with eyes, toothpicks, water, potting soil and a supply of liquid plant food. Students should pour water into two of the glass containers until the water is almost at the top. Students are instructed to stick toothpicks evenly spaced around two of the pieces of potato. These toothpicks will rest on the top of the jar and hold the potato suspending in the water. The toothpicks should be placed so that the eye of the potato will be under the water when the potato is suspended in the jar. The third jar should be filled 1/2 of the way with soil. Students should place the third piece of potato in the jar with soil and finish covering the potato with additional soil.
Water the soil until it is moist, but not wet. Add 5 drops of liquid plant food to one of the glass containers with water. Label that container with a black marker. Set all jars in a sunny location and observe the growth of the potatoes for two weeks. Water the soil as needed to keep it moist. Students should write down observations daily on the growth of each plant. Take pictures if desired for later review. Students should compare their data with other students to determine if everyone had the same results. If they did not, determine why not. The potato with the nutrients in the water should have grown the fastest. This experiment will introduce students to the idea of hydroponics.
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Hydroponics is the process of growing plants in a liquid instead soil. This method of growth allows gardening in areas where it would not be possible under normal circumstances. People who live in cities with no access to a plot of ground can use the method to grow vegetables if they have a sunny location. Some groups will use rooftops when they are available. Hydroponics is limited however by the need for nutrients in the water. Large vegetables such as corn do not grow well hydroponically. Vegetables that are grown in liquid may not contain all of the normal nutrients and therefore not be quite as healthy as those grown in soil. The science of hydroponics continues to evolve.
Growing a potato in water as a science project is a first step in learning more about how plants grow and how people can influence this growth.
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http://imnh.isu.edu/digitalatlas/teach/lsnplns/potaoelp.htm - Idaho Museum of Natural History